I’m not sure what you think we might be able to say, other than to repeat the exchange we had in this thread: A specific subtitle is centered
Which ended when you said the problem went away, leaving us no clearer about what was special or different in the project where it didn’t work.
So you’ll need to go back through that thread (and it really would have been better if this post had been a followup there, instead of splitting it into a new one and leaving people to search for the previous conversation) and the steps we requested there - because if nobody else can reproduce it, it makes it hard for anyone but you to explore why this (eventually?) happens to some of your projects.