diff --git a/Core_Cata.lua b/Core_Cata.lua
index efa81a56..0ae7f9c6 100644
--- a/Core_Cata.lua
+++ b/Core_Cata.lua
@@ -192,6 +192,15 @@ function F.IsGroupTypeHidden(layoutGroupType)
     return layoutGroupType and Cell.vars.layoutAutoSwitch and Cell.vars.layoutAutoSwitch[layoutGroupType] == "hide"
 end
 
+--! The layout a frame group has to be laid out for, from the same mapping: nil when that entry is "hide"
+--! (or unknown), so a frame group can lay itself out ahead of time for a group type the player is not in.
+function F.GetGroupTypeLayout(layoutGroupType)
+    local layout = layoutGroupType and Cell.vars.layoutAutoSwitch and Cell.vars.layoutAutoSwitch[layoutGroupType]
+    if layout and layout ~= "hide" and CellDB["layouts"][layout] then
+        return layout
+    end
+end
+
 local bgMaxPlayers = {
     [2197] = 40, -- 科尔拉克的复仇
 }
diff --git a/Core_Mists.lua b/Core_Mists.lua
index 4a91d8d1..a9b9d70e 100644
--- a/Core_Mists.lua
+++ b/Core_Mists.lua
@@ -212,6 +212,15 @@ function F.IsGroupTypeHidden(layoutGroupType)
     return layoutGroupType and Cell.vars.layoutAutoSwitch and Cell.vars.layoutAutoSwitch[layoutGroupType] == "hide"
 end
 
+--! The layout a frame group has to be laid out for, from the same mapping: nil when that entry is "hide"
+--! (or unknown), so a frame group can lay itself out ahead of time for a group type the player is not in.
+function F.GetGroupTypeLayout(layoutGroupType)
+    local layout = layoutGroupType and Cell.vars.layoutAutoSwitch and Cell.vars.layoutAutoSwitch[layoutGroupType]
+    if layout and layout ~= "hide" and CellDB["layouts"][layout] then
+        return layout
+    end
+end
+
 local bgMaxPlayers = {
     [2197] = 40, -- 科尔拉克的复仇
 }
diff --git a/Core_Vanilla.lua b/Core_Vanilla.lua
index 9290bd8b..b7c6aaef 100644
--- a/Core_Vanilla.lua
+++ b/Core_Vanilla.lua
@@ -197,6 +197,15 @@ function F.IsGroupTypeHidden(layoutGroupType)
     return layoutGroupType and Cell.vars.layoutAutoSwitch and Cell.vars.layoutAutoSwitch[layoutGroupType] == "hide"
 end
 
+--! The layout a frame group has to be laid out for, from the same mapping: nil when that entry is "hide"
+--! (or unknown), so a frame group can lay itself out ahead of time for a group type the player is not in.
+function F.GetGroupTypeLayout(layoutGroupType)
+    local layout = layoutGroupType and Cell.vars.layoutAutoSwitch and Cell.vars.layoutAutoSwitch[layoutGroupType]
+    if layout and layout ~= "hide" and CellDB["layouts"][layout] then
+        return layout
+    end
+end
+
 -- layout auto switch
 local instanceType
 local function PreUpdateLayout()
diff --git a/Core_Wrath.lua b/Core_Wrath.lua
index c4b3b949..3d884b51 100644
--- a/Core_Wrath.lua
+++ b/Core_Wrath.lua
@@ -192,6 +192,15 @@ function F.IsGroupTypeHidden(layoutGroupType)
     return layoutGroupType and Cell.vars.layoutAutoSwitch and Cell.vars.layoutAutoSwitch[layoutGroupType] == "hide"
 end
 
+--! The layout a frame group has to be laid out for, from the same mapping: nil when that entry is "hide"
+--! (or unknown), so a frame group can lay itself out ahead of time for a group type the player is not in.
+function F.GetGroupTypeLayout(layoutGroupType)
+    local layout = layoutGroupType and Cell.vars.layoutAutoSwitch and Cell.vars.layoutAutoSwitch[layoutGroupType]
+    if layout and layout ~= "hide" and CellDB["layouts"][layout] then
+        return layout
+    end
+end
+
 local bgMaxPlayers = {
     [2197] = 40, -- 科尔拉克的复仇
 }
diff --git a/Modules/Layouts/Layouts.lua b/Modules/Layouts/Layouts.lua
index cb007610..a60b931a 100644
--- a/Modules/Layouts/Layouts.lua
+++ b/Modules/Layouts/Layouts.lua
@@ -1831,6 +1831,10 @@ local function GetDropdownItems(indices, groupType)
                     -- LoadLayoutDB(Cell.vars.currentLayout)
                     UpdateButtonStates()
                     -- UpdateEnabledLayoutText()
+                elseif Cell.vars.layoutGroupType then
+                    --! frame groups are laid out ahead of time for the group types the player is not in
+                    --! (see F.GetGroupTypeLayout), so let them pick up the new assignment
+                    F.UpdateLayout(Cell.vars.layoutGroupType, true)
                 end
             end,
         })
diff --git a/RaidFrames/Groups/PartyFrame.lua b/RaidFrames/Groups/PartyFrame.lua
index 66646fcf..1801fe2a 100644
--- a/RaidFrames/Groups/PartyFrame.lua
+++ b/RaidFrames/Groups/PartyFrame.lua
@@ -116,7 +116,20 @@ local function PartyFrame_UpdateLayout(layout, which)
             RegisterAttributeDriver(partyFrame, "state-visibility", "[@raid1,exists] hide;[@party1,exists] show;[group:party] show;hide")
         end
 
-        if Cell.vars.groupType ~= "party" then return end
+        -- Layout: applied for every frame group, not only the active one, so that the first show of a group
+        -- type since login can happen in combat. F.UpdateLayout defers itself until combat ends, so a party frame
+        -- that had never been active came up with no sizes, anchors or header attributes when the group changed
+        -- in combat, and stayed blank until combat ended. See F.GetGroupTypeLayout.
+        if Cell.vars.groupType ~= "party" then
+            local ownLayout = F.GetGroupTypeLayout(Cell.vars.partyLayoutGroupType)
+            if not ownLayout then return end
+            if which then
+                -- partial update from the Layouts tab: only relevant when the edited layout is the one used here
+                if layout ~= ownLayout then return end
+            else
+                layout = ownLayout
+            end
+        end
     end
 
     -- update
diff --git a/RaidFrames/Groups/RaidFrame.lua b/RaidFrames/Groups/RaidFrame.lua
index 3bfcab2a..3aab04d0 100644
--- a/RaidFrames/Groups/RaidFrame.lua
+++ b/RaidFrames/Groups/RaidFrame.lua
@@ -279,8 +279,9 @@ function F.GetRaidFramePoints(layout)
     return point, anchorPoint, groupAnchorPoint, P.Scale(unitSpacing), P.Scale(groupSpacing), P.Scale(unitSpacingX), P.Scale(unitSpacingY), verticalSpacing, horizontalSpacing, headerPoint, headerColumnAnchorPoint
 end
 
-local function UpdateHeadersShowRaidAttribute()
-    if Cell.vars.currentLayoutTable["main"]["combineGroups"] then
+local function UpdateHeadersShowRaidAttribute(layout)
+    -- NOTE: layout table passed in, the raid frame can be laid out for a layout that is not the current one
+    if layout["main"]["combineGroups"] then
         combinedHeader:SetAttribute("showRaid", true)
         for _, header in ipairs(separatedHeaders) do
             header:SetAttribute("showRaid", nil)
@@ -366,7 +367,20 @@ local function RaidFrame_UpdateLayout(layout, which)
             RegisterAttributeDriver(raidFrame, "state-visibility", "[@raid1,exists] show;hide")
         end
 
-        if Cell.vars.groupType ~= "raid" then return end
+        -- Layout: applied for every frame group, not only the active one, so that the first show of a group
+        -- type since login can happen in combat. F.UpdateLayout defers itself until combat ends, so a raid frame
+        -- that had never been active came up with no sizes, anchors or header attributes when the group changed
+        -- in combat, and stayed blank until combat ended. See F.GetGroupTypeLayout.
+        if Cell.vars.groupType ~= "raid" then
+            local ownLayout = F.GetGroupTypeLayout(Cell.vars.raidLayoutGroupType)
+            if not ownLayout then return end
+            if which then
+                -- partial update from the Layouts tab: only relevant when the edited layout is the one used here
+                if layout ~= ownLayout then return end
+            else
+                layout = ownLayout
+            end
+        end
     end
 
     -- update
@@ -414,7 +428,7 @@ local function RaidFrame_UpdateLayout(layout, which)
     end
 
     if not which or which == "header" then
-        UpdateHeadersShowRaidAttribute()
+        UpdateHeadersShowRaidAttribute(layout)
     end
 
     if layout["main"]["combineGroups"] then
diff --git a/RaidFrames/Groups/SoloFrame.lua b/RaidFrames/Groups/SoloFrame.lua
index 4d3e8a6e..c0a7f730 100644
--- a/RaidFrames/Groups/SoloFrame.lua
+++ b/RaidFrames/Groups/SoloFrame.lua
@@ -44,7 +44,20 @@ local function SoloFrame_UpdateLayout(layout, which)
             RegisterAttributeDriver(soloFrame, "state-visibility", "[@raid1,exists] hide;[@party1,exists] hide;[group] hide;show")
         end
 
-        if Cell.vars.groupType ~= "solo" then return end
+        -- Layout: applied for every frame group, not only the active one, so that the first show of a group
+        -- type since login can happen in combat. F.UpdateLayout defers itself until combat ends, so a solo frame
+        -- that had never been active came up with no sizes, anchors or header attributes when the group changed
+        -- in combat, and stayed blank until combat ended. See F.GetGroupTypeLayout.
+        if Cell.vars.groupType ~= "solo" then
+            local ownLayout = F.GetGroupTypeLayout(Cell.vars.soloLayoutGroupType)
+            if not ownLayout then return end
+            if which then
+                -- partial update from the Layouts tab: only relevant when the edited layout is the one used here
+                if layout ~= ownLayout then return end
+            else
+                layout = ownLayout
+            end
+        end
     end
 
     -- update