In SWTOR I noticed that my helmet was not visible during my conversation with my companion. I have Hide Head Slot disabled. This only started happening after I turned off dark side corruption. If it helps, my adv. class is the Sith Sorcerer. For some conversations I can see my helmet but for others I cannot.
This only happens on the ship. I use the Reaver's Headgear.
Best Answer
Unfortunately the game is simply buggy in this regard. For whatever reason it appears that cutscenes do not share code for checking things like hood toggles, and QA was not tight, so individual cutscenes will vary in what they do right and what they do wrong. You'll very often see this issue with companions as well — showing helmets that they shouldn't show, or the reverse, or magically appearing in their default gear instead of what you have equipped on them. There are also minimal headpieces that erroneously modulate voices as if they were fully enclosing the mouth.