To any wayward wanderers of the future, one trick that worked for me is to do the bone hiding inside AYourCharacterClass::BeginPlay()
For some reason it doesn’t work if done in a constructor, or at least I am unable to get it to work.
EDIT: I should also note that as far as I can tweak it, if you hide a bone, Unreal will hide all child bones. It works for me as I’m trying to hide a whole arm, but yea I don’t know how to do that use case. Here’s a thread for just this issue btw Hide/Unhide a specific bone by name - #3 by dodolfo44