I'm working with a GameMaker Studio 2 programmer, but one of my animations are missing the attachment Images while it is playing in the game build. I will probably ask in the GMS forums as well, but I want to figure out this confusing problem as soon as possible. Out of 19 attachment images, only 1 is displayed when implemented in GMS2. I made sure I keyed their attachment visibility as on in the Editor, but the result in GMS2 doesn't reflect what I see in the Editor. A strange thing is, I made a test animation and the attachments are displayed fine in GMS2.
So, I can't pinpoint the reason if I made an error in the Editor. Each image attachments have their own slot and the slots are parented to their own bone. There is Draw Order and Opacity keys as well.
Spine 3.7.94 Pro
Update to my situation. I somehow fixed it and isolated the error to my side in the Editor.
The problem lied with the Clipping Mask I applied to only influence one slot, but it somehow made all the Slots in front of it invisible when applied in GMS2. So, I moved the Slots containing the attachments behind the Clipping Mask Slot and marked the End Slot again just in case.
My theory is that something went wrong when I rollbacked the .json from 3.8 to 3.7. It might have terminated the End Slot data of that Clipping Mask.