There’s still some race conditions and multi-threading problems, specifically with asset types that we might not test as much internally.
Here’s an example of the type of issues with found in a recent test in Fortnite with thread sanitizer and ALT enabled:
- CDO being postloaded can be accessed by ALT
- OnObjectRenamed multicast delegate called from ALT
- One race in ClearImportedPackages on GT while IncludePackageInSyncLoadContextRecursive is called on ALT
- One race in FPackageName::QueryRootContentPaths().
- Multiple race between FApp::IsGame() and SetPlayInEditorWorld/RestoreEditorWorld during PIE
These are just internal notes and not any kind of exhaustive or representative list.
Overall the ALT in Editor is not ready for production yet, which is why it’s still disabled.
It might work for your case if you have a simple project but it’s also possible you’ll see crashes and problems as result of enabling the ALT right now.