Do you see these materials properly assigned at your _SkeletonData.asset?
Yep, when first brought in they are properly assigned.
In general there should be no need to manually assign anything, unless you are using an older spine-unity runtime version (3.8 or older)
Ahh, excellent and good to know. In that case you may find it interesting that if you do choose to assign them (now I know is not required) to the _Atlas.asset, close Unity, delete the /Library/ folder, re-open Unity, only the one default material is re-generated but not the others (Screen, Multiply). Which then, source control software may get the user tripped up showing that previously commit materials were deleted. Likely most people aren't hitting this so just a strange edge case we accidentally got ourselves into. Not sure if you all would consider that a bug or not?
Which skeleton component are you using, SkeletonAnimation / SkeletonMecanim or SkeletonGraphic?
We typically work with SkeletonAnimation.
Thanks as always Harald!