Sorry to bump this old thread but did you find a fix for this?
I have the exact same issue in UE5, loads the startup map no issues, however, the moment I try to load another level (any) it crashes:
Fatal error: [File:D:\build++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorServer.cpp] [Line: 2043] World Memory Leaks: 2 leaks objects and packages. See The output above.
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_AssetTools
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_ContentBrowserAssetDataSource
UnrealEditor_ContentBrowserAssetDataSource
UnrealEditor_ContentBrowserAssetDataSource
UnrealEditor_ContentBrowser
UnrealEditor_ContentBrowser
UnrealEditor_ContentBrowser
UnrealEditor_ContentBrowser
UnrealEditor_ContentBrowser
UnrealEditor_ContentBrowser
UnrealEditor_ContentBrowser
UnrealEditor_Slate
UnrealEditor_Slate
UnrealEditor_Slate
UnrealEditor_Slate
UnrealEditor_ApplicationCore
UnrealEditor_ApplicationCore
UnrealEditor_ApplicationCore
UnrealEditor_ApplicationCore
user32
user32
UnrealEditor_ApplicationCore
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
kernel32
ntdll
Edit
The only workaround I have found to this for the time being, was setting the map I wanted as the editor startup map in the project settings and then reopening the project…
(This needed to be done for every level that I wanted to switch to)