Not a Regression.
//UE5/Release-5.0 CL 18747223 Source-GitHub
//UE4/Release-4.27 CL 18319896 Binary
"The crash test code is located at Source/HashBucketLockedBug/Private/Bug.cpp, every step in the code contain technical explanation.
After creating many objects while iterating an outer, the hash bucket of the outer is read-locked permanently, causing the ReadOnlyLock check to fail inside FHashBucket::Add, with the following fatal error:
Fatal error: [Link Removed] [Line: 104]
Trying to add TestObject /Game/TestPackage.TestPackage:LotOfObjectsInside.CrashingObject to a hash bucket that is currently being iterated over which is not allowed and may lead to undefined behavior!
Note that the object / hash bucket is not being iterated at the time of the creation of the object.
The crash must be caused because ThreadHash.ObjectOuterMap is rebuilt while iterating: the Inners variable in ForEachObjectWithOuter point to a memory location that was previously freed (the outer map is rehashed while iterating)."
4. In the ActorBug.cpp delete everything then paste in the following code:
5. Save in Visual Studio then Compile in Editor using the "Recompiles and Reloads C++" button in the lower right corner of the editor.
6. Drag and drop the ActorBug into the level then Play in Editor
All of objects should be created without causing issues to the outer being iterated.
Editor Crashes with a Fatal Error in UObjectHash.cpp Line 319
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-141815 in the post.