How do I address a transgender or gender fluid officer?

Worry about UCMJ changes when they actually happen.
Go by uniform or hair. If you still aren't sure, skip the gendered address (yes sir, yes ma'am) and just use rank (yes, Captain, yes, LT, etc.). If you misgender someone and they correct you, then you know, so don't do it again. If you see someone out of uniform and need to inquire about their pronouns, just be polite about it. "Which pronouns do you prefer?" Is good phrasing.

its how they announce them selves, you accept it and respect them just any other human being.

I do not, for one moment, believe this is a legitimate question. It's a straw-man argument meant to get people to agree with you or pat you on the back.

Fuck how they identify. Sir or mam, not anything else. If they bring up anything in their personal life to a junior rank, they have no business leading anyone.

PFC Timothy Mangum, Speaking from experience I have always gone with my gut and then the individual will correct me for future reference. They are almost always self-deprecating in their response as if they get it all the time, at least that has been my experience. Once you know, just be sure to remember next time. Then and only then should you worry about some type of reprimand. The best rule of thumb is to always be honest. If you didn't know, you didn't know, but you can learn from your mistakes.

Rank and name works every time.

What's wrong with addressing the "It" as Lt, Major, or whatever rank?

Putting the cart before the horse there kid. If and when UMCJ is changed for that, there will be a published policy telling you How to address them- worry about making SPC instead

I don't see how one can go wrong if one uses just Rank and name.

That makes it easier than civilian life.

Throughout the History of the Military it has been Okay to address all Soldiers buy Rank. Things can get confusing just be respectful by rank if they want addressed by something else they will request it and you follow suit. Just short story from and old Soldier I was in Ft. Carson Colo. Working the Turret of a Tank Head down and feet up. I heard some one enter the tank through the loaders Hatch They spoke, How's it going if here Being in a tight spot and not being able to see and getting a little flusters, I Said: well s... if I were smaller I might get this done this year however that's not the case, Hey can you hand me that f...in Ratchet. He did and did not leave I got what I needed done and crawl out of my head stance position and came face to face with a full Col. I was red in the face and said sorry sir. Kind of hard to see from down there Sir. He just Laugh told me it was okay and said he did not identify him self because he thought I might hurt my self trying to get out of there and stand at attention. We chatted a bit and off he went every time I seen him after that he addressed me as his turret rat and I was okay with that.