MS Flight Sim is a curse! I'd be surprised if you aren't focusing on the instruments and chasing the performance instruments if MSFS has seen a lot of use. I'd say you need to break the instrument focus habit, to be replaced with external reference points. You could ask your instructor to cover the instrument panel *and* re-emphasize the external reference points appropriate to your aircraft. The idea is that you align the bits you can see out of the windscreen with the natural horizon. Do the exercise when it's smooth and with good visibility to the Hz - even if it means an early morning start.
At various points in the turn your instructor can expose the panel for you to check the performance then cover it again. Make any attitude adjustment using the outside reference points, not while looking at the panel (you can't refer to the panel if it's covered!).
Don't do a single 180 or 360 turn. Do two or three before rolling level again. The goal is to focus on the external cues with just an occasional check of the instruments and then *small* attitude adjustments using those outside cues. With some practice you'll be able to do enter, maintain & exit accurate turns with minimal reference to the panel.