So I have an editor tool that allows one to select an animation and it adds animation events at specific times. Anyways the tool works just fine in Unity 5.5,5.6, and 2017.3 . Now I know this is very weird but in Unity 2017.2 whenever I select a humanoid animation, as soon as the importer is set to dirty it crashes. It works just fine in the other versions mentioned here. It also works fine with generic animations, however if I change a humanoid to a generic and then try to use it it still crashes. Weirdest thing ever. Any suggestions? Also although it does not crash in 2017.3 whenever I select a humanoid animation I get InvalidOperationException: Operation is not valid due to the current state of the object
If you can reproduce the crash, could you please submit a bug-report following the advice given in this document.
While this does not help you immediately, it allows UT to stabilize their software in the long(er) run.