We’ve recently had the same issue on 5.6.2 using Perforce. Our Uncontrolled Changelist had ~9000 files from the engine folder. Tried reverting + verifying engine after it crashed, but the list was still there.
One workaround we used was disabling uncontrolled changelists from project settings. However, we kept getting validation errors when saving assets that used stuff from the engine (i.e. “for loop” macro wasn’t found for add), so we also had to disable Validate on Save.
We found a better solution shortly after. The editor created a “UncontrolledChangelists.json” file in Project → Saved → SourceControl . It looks like this:
(We previously tried moving the items to another changelist “ENGINE FILES” and deleting that from inside the editor, but it didn’t work)
We edited out the entries so that the json looks like this:
Otherwise, removing the entries in “files”: […] should do the job.
On reopening the editor everything went back to normal and we could revert the previous workarounds.
The View Changes window still shows
But as long as we don’t reconcile from inside the editor everything is fine. Hope this helps!