I've noticed that if you have picked or purchased any necklace item prior to starting the mission where you get your appearance changed to meet up with the reporter, when you return to the clinic you can no longer change your appearance and you get soft locked into just having to be whatever the mission turns you into as the customize cheat tool also does not function. This error does not occur if you have not obtained a necklace item. Which I mean, kinda ruins the game if I'm honest.
The only time I changed the hair color was at the beginning of the game. in creation I made Sammy a custom white-blonde. Never changed it otherwise. Once I completed the mission in question, if I had a necklace item, it soft locked and I could not change anything. So, I did a run where I picked a default character and speed ran to the mission not picking up anything or changing any appearance value. It worked just fine.
But then, to further test this, I did another new game and did the same speedrun without changing any appearance value but the only exception was I stopped and purchased the first necklace I came across from wandering around the stalls and it soft locked me again. So what happens is when you go to change appearance after the mission is over, it gets locked in the necklace accessory screen and you cannot cycle any of the other tabs.