Sorry I didn't replied before.
Mmm... I don't understand why you'd need the project file (?). :notme:
My question was more about if what I've described is intended behavior on Spine editor's part or not.
Sooo... is it, by chance, implied by your request that 'attach off' keys at frame 0 should not be cleared, so something must be bad in my project? (therefore your need to see it?)
Thank you!
We can't tell if the keys are being deleted for a good reason without seeing your project. Attachment (and other instant keys, like draw order) are deleted at the beginning on an animation if they are the same as the setup pose. Also, keys that are the same as the previous keys are deleted.
Nate wrote...are deleted at the beginning on an animation if they are the same as the setup pose.
This! 
My setup pose indeed has those attachments hidden by default. So it's intended behavior...
I was using those keys to make sure they were not active at animation start, because I've being observing that attachments that are not part of a skin or the setup pose tend to 'magically' disappear when I use SetupEmptyAll at runtime.
This opens up new questions, but as they're not related to the OP, I'll shut up here and make a new thread when I have some spare time and a clear head.
Thank you guys! 
Great, I can always appreciate when there is no bug. 
Hopefully the behavior works for you. Assuming you are using AnimationState, when animations are no longer playing they should result the values they changed back to the setup pose, so you should not lose your setup pose attachments.
Nate wroteGreat, I can always appreciate when there is no bug.
Well, to be honest my problem is just the opposite...: my heroine loses her hard earned... erm... face "attachment" (lol) if I let the setup pose take over at some point in the animation flow. :notme:
But.. yeah, maybe not the place to discuss this.
Aaand... it seems that all the info I need about this problem of mine is in here: 3.5+ Attachments And Mixing
Mmm... ok. :wonder:
