Just as an uninformed suspicion:
I did (and still do) this thing where I set up a complicated pose (along with slot image keys) and save them into the project as animations with 0 duration. I do this so I can copy this pose and paste it into certain points in an actual usable animation.
I vaguely remember something about these anomalous keys that shouldn't be there when I imported skeletons from one project to another (projects where I did a lot of the copying and pasting of those complicated poses)
So, my suspicion is: something up with copy-paste. XD Dunno if that makes sense.
I could just be confusing the matter with something that already got fixed.
In any case, I hope serendipity is on your side in finding the bug. :p
