I left a comment on https://developer.blender.org/T73863 that may be pertinent to other bugs in this list. TLDR: I cloned Blender and looked into the bug, found out the issue involved FBX's scale inheritance being fixed at "RSrs" instead of accounting for bones' Inheritance Type. More troublingly, however, is that other software packages do not appear to deal with "Scale Compensation" consistently or correctly. Please see the comment for more details.
Sep 29 2020
May 28 2020
I should give an update, this may help in decision-making:
Feb 20 2020
I think this is the same as the bug I recently filed, maybe these should be merged? https://developer.blender.org/T73863 Haven't tried DAE though. I described the fix you tried and why it doesn't generally work.
Feb 18 2020
Thanks for acknowledging this issue, hopefully someone takes a look at it soon! If I get some time, I might see if I can get involved, though I'd specifically want to work on this problem.
Feb 16 2020
Feb 10 2020
I'm having the exact same issue in 2.81, and this is definitely a bug, since the checkboxes don't appear to be doing what they say they do. If it's not possible to fix this, then perhaps the checkboxes should be removed? In any case, please re-open this issue.
Jan 29 2020
Are we still taking requests? If so...
Jan 28 2020
Alright, that makes sense I suppose. Can we put this on a feature request list or something? I feel like this is an important issue that affects Blender’s usability, and should be addressed at some point. It really makes animating a subsurfed rig more of a headache, and I believe other software actually supports this.
Jan 27 2020
Hmm, well my file was failing for 2.81, so either it’s a separate issue after all, or something else about 2.81 is obfuscating the issue for only the other file.
Jan 26 2020
Jan 25 2020
Jan 13 2020
Any ETA on GPU acceleration for OpenSubdiv? Animation with subsurf in 2.81 appears to be very slow.
Dec 16 2019
I've gotten this issue multiple times now, on Blender 2.81. Didn't get a message on crash, was instantaneous on undo/redo (can't remember which one), and not seeing a log in a "temp" folder, either in C:\ or C:\Users\<User>\AppData\Local\Temp. Attached my "system info" file. It's worth mentioning I do occasionally get script errors during undo/redo, I'll try to watch for them next time it happens (I assumed they were logged, but I can't find a log.)