Right thanks for pointing that out
Posting about this the second time on reddit resurfaced some key info in my head regarding the whole scenario and I forgot to come back over here and edit the post
Here's some food for thought: The bug remains regardless of whether or not I have mods active
Furthermore at one point I tried using "Small changes in the UI" by vito740 but this had major conflicts with controller mode and I had to uninstall it
With 'no mods active' you mean starting a new game or did you only deactivate mods in the mod menu and continued playing from a save where the mod was still active ?
Mods cannot be deactivated for a running game as far as I know. You can use brute force and delete a mod which would only mean that the game might not find resources needed anymore, the story code would not change I think.
That's the case at least for my mod because it has tons of story code.
I still fail to understand why playing an effect on 'Bip Head' could lift a helmet and I don't think it does. Could only be that a played effect shifts the effect bone up and a shifted effect bone is then used as the anchor for helmets to be placed. If it's that, then it must be a bug I guess. But I don't know if it's the effect from my mod.