Harald :Is the red lid part of the default skin?
No, the default skin is empty and only the lights that come out of the box appear there.
Harald :Do you have any keys in your animation that change attachments?
No I have different bones with separate skin placeholders that are enabled on each scenario. When "small box" skin is selected, the "big box" skin placeholders (which are on a different bone) are empty.
Harald :If so, did you perhaps enable Animation cleanup in the Spine export settings?
I had Animation cleanup enabled yes. I tried another export disabling it and the situation now changed. All the small boxes appear correctly on runtime, and the big boxes appear without a lid.
Harald :How do you assign your skins?
string skinName = "mySkin";
skeleton.Skeleton.SetSkin(skinName);
Harald :Which version of the spine-unity runtime are you using
version: spine-unity-4.0-2021-08-16.unitypackage
I'll try to provide a minimal unity project for better understanding.
Regarding the side note: yes I get it but atm I cannot share more visual info unfortunately.
Thanks a lot for answering in such detail