Thanks. I've confirmed we've received it. We'll take a look at it.
Stay tuned!
It seems to be missing a lot of pages. This atlas is looking for 25 pngs.
I can confirm this skeleton was exported with Spine 3.7.
The fade-out slot color animation on the Z's look correct when using 3.6 but don't 3.7.
I looked at the slot color keys on the animation and it looks like they don't start at 0.
So it looks like this in the Spine editor dopesheet.
This may be an ambiguity to tackle for the runtime design.
But for immediate results, I recommend adding a slot color key at the start of the animation so that it's clear to the runtime how to animate this color.
This applies to all runtimes, not just Spine-Unity.
Sorry! There seems to be something else going on in spine-unity. We're checking it right now.
We found a problem and it's been fixed in the latest update!
You can get the latest unitypackage here: Spine Unity Download
Thanks again for reporting and taking the time to send us the repro case!