Sorry to point out the obvious, but assuming this is not easily or quickly fixable on Epics part (you will have to wait for 1-2 releases at best), why not just use your own vigilance; either always commit P4 Changelists via the Editor, or close the Editor and submit through P4V before re-opening? I’m not trying to be rude here, I happen to work in a game studio where artists were always mixing their method of submit and it did cause issues (mostly status in the Editor, we have never seen what you are describing); I simply asked people why they were doing this and they didn’t really have an answer, as their isn’t really any reason to do it [mix method of submit], so I basically told them to pick one method and stick with it…haven’t heard an issue come up since.
As for repairing your assets that are not loading and/or crashing the editor; what steps have you taken to isolate or debug them? Can you provide these assets and/or logs/debug info for their crashes? If so, you should provide all of this info on your AnswerHub request as it will make it into the hands of a developer much more quickly.
Also, how is removable media a workaround for your problem? Assuming you are implying that you are now simply “sharing” file changes using this method you are already having to close and re-open the editor to accomplish this; so replace your USB drives with P4V actions.
Lastly we have submitted over 3k changelists to Perforce for our UE4 project, some people using the Editor directly (mostly content developers) and some who exclusively use P4V (mostly engineers) and what you are describing has never happened; I’m thinking something is very unique about your situation/setup, otherwise many more people would be seeing this.