Thanks, psussi, for all the files.
I’m sorry that you run into those troubles. This seems to be not solvable from my side. I will file a report after I have finished this post here.
Here is an example with your file (no polygon model, just joints) how it should work. This is R21. I would think it is based on the complete new reworked Viewport code. No excuse, just stating a suspicion.
https://www.amazon.com/clouddrive/share/UbACubPYO6LMBriHGQ8kLWq00BrDkwCDibWm1HYXy7h
You can contact, of course, the support as well, to get another perspective about it.
A few things, I have dragged the Polygon object out of the hierarchy, and the clips. If you keep them there, you have to keep something there always, and any animation clip you have saved needs then an object (at least there), which might make this less compatible. If a clip has stored animation there, for that polygon object, it will interfere with the animation, mainly when looped, and then the object isn’t required to do so., etc. Just my 2cents.
I hope that this will be patched ASAP. Until then, please note that it can be disabled in three places. In the viewport filter, in the clip and as another option in the Motion System tag (Attribute Manager).
I checked all combinations, with all viewport Display setting options, hence the time I needed. Nothing was able to give me what R21 does. Sorry about that. However, I’m sure that it is only a temporary annoyance.
Sorry that your studio has to deal with that during an evaluation time since all is new, and it feels more stress full, I guess. I reread the manual, just in case.
I will check the next published iteration and share the news here.
My best wishes, stay safe, stay healthy.