There is an unofficial integration which seems to work well. The next integration that we release will add UMA integration that I create though. I have it working for third person, just need to figure out first person.
Destroying assets is not permitted to avoid data loss.
If you really want to remove an asset use DestroyImmediate (theObject, true);
Make sure you're not rebuilding your skeleton in the Dynamic Component Avatar component (Rebuild Skeleton checkbox) . This is one reason for which it could happen.I was wondering if it happens on me only before reporting. ^^