I'm pretty much 'out' at work. I wear 100% feminine clothes, less androgynous now. Spoken with HR and several managers. I still get sir, Mr, etc. While it bugs me, I tend to ignore it.
One manager I made a point of asking to drop the Mr and Sirs .. sure thing "OK, Man, no problem" ... really? Habit responses are hard to break.
HR lady, I gave her a DR. summary that specifically highlighted 'gender identity' .. she said, "thank you, sir". You'd think an HR person would be more careful. Nope .. habits.
They respond to what they perceive or out of habit, try not to let it get to you. If they do it on purpose and spitefully then the issue is much worse. As you're presenting male, they are doing nothing amiss.