Appreciate the details about the problems you are having Matt.
The symptoms you are describing are not indicative of the lack of the collaboration feature (the red circle). When we turned off this feature in December, we had an issue wherein some users were erroneously seeing more people collaborating on their files, when they were not. To elaborate, next to the red circle we indicate who has the file open (could be one or more users). During that incident even though a file was being worked on by a single user, Fusion was wrongly indicating that more people were working on that file. We turned off the collaboration feature but could not clean up this erroneous collaboration data. We are deploying a fix for that soon. If you have such files, the one side effect you will see is that you will not be able to delete such files. You should not see any other problems.
The problem you are seeing about the drawing files being corrupted must be due to some other issue. I will forward this issue to the appropriate team. Sorry that you are encountering this problem.
Regards
Gautham
Gautham Kattethota
Software Development