I’ve come across a somewhat obscure issue with blending two animation clips together when either of the clips has its Weight set to something other than “1”.
In short, if you set the Clip Weight of an animation clip to something less than 1, that weight isn’t properly used when blending between its neighboring clips.
Here’s a short video showing the behavior in an extreme case:
This appears to be the result of AnimatorTrack.UpdateClip, where compountClipsWeight is simply set to “1” if there are 2 or more clips. It seems that really needs to take the clip weights of both clips into account.
This is probably a bit obscure, as it seems to only be an issue when the animation track itself is a secondary track being blended on top of a lower animation track. But I’m also not really sure how to deal with it, as the transitions always have a bit of a “snap” to them if one of the tracks has a clip weight assigned to it.