This has been a recurring issue I’ve seen more often over the past years, I suspect the system that after some time renders the final version of the portrait and stores it in the portrait database for the game to use is down again.
As result you can keep making new portraits in your client but nothing ‘sticks’, and reverts to the last stored portrait.
If it is as before I expect newbies will be entering the game without portraits the coming days and rookie help chat will have an increasing number of empty portraits until this eventually is fixed again. Usually that takes a few days.
Try again in a couple of days and/or send a bug report (F12) ingame to catch their attention.
Changed one of my portraits yesterday, again today, and while the character sheet in-game and full bodyportrait show the new clothing/style, the portrait and everything else in-game (and in the Launcher) is showing the old one…