The engines on the a330 in infinite flight are not that powerful to climb straight up to FL400. I have had this situation happen to me on many occasions.
I had the same issue. Violation won’t be remove as it wasn’t a IF in game issue. I was climbing too fast for my load in the a330 after an hour my plane fell out the sky. What I would recommend is to wait till your aircraft reaches cruising altitude make sure you aren’t losing speed. Also maybe consider cruising at a slightly lower altitude. How loaded were you?