Models placed in a group different than the entity part sometimes appear in the wrong location (?)
Adding a model to a group different than the entity will randomly switch between the correct position and 'invalidbone'. This might because the entity forces LOD0 by default which seems to fix the problem but I guess it depends on which part loads first.
Video: https://i.imgur.com/1lHCRok.mp4 Outfit: different_group.txt
Placing a model in the same group as the entity but not attached directly to the entity seems to work.
Video: https://i.imgur.com/zgpe8vs.mp4 Outfit: same_group.txt
Tried with some playermodels. Models with only one LOD don't get this issue. "proper" Source games put many LODs, while most addons' models have only the one maximum detail level. Seems like an accurate path to the cause, roughly speaking.