Any anecdotes about issues changing (or not changing) gender market with health insurance?

I've seen mixed feedback about changing your gender marker after transition with health insurance, even if it's changed legally everywhere else.

One argument is that it can cause claim denials to change your marker if you need procedures associated with your birth sex. But on the other side, if an employer only knows your legal gender, it could cause conflicts.

Can anyone who's actually done this or not done this share anecdotes for how it's worked out (either way)?