There is zero reason to show the default portrait when one exists.

[Astronis]

all gearset portraits are stored locally on ur harddrive. Every time u join a duty - ur portrait is being uploaded, and verified. They check stuff and check if u did not alter it with 3rd party software.

You can also transfer portraits between characters, for all the good that will do. When I make new alts I copy over a lot of my character folder so I don't have to redo hotbars and UI settings, and end up with 40 portraits the game needs to check if this alt is the right race, right sex, right skin color, right gear, and right job before it gets to the glams.

That's a good thing to check for, however it is clearly checking a lot more than that, and being tripped up by ingame items that I own being replaced by other in game items that I own. Is there any ingame item that is not allowed in a portrait?

If your portrait were on the very edge of being able to be saved, a different item *could* push it over the edge. Probably not, but I could see on some of mine a different shaped weapon potentially doing something like that by pushing the camera around or maybe blocking too much of my character's face in a way that triggered the check. Possibly a game update might have subtly changed the acceptability check as well.

I also have one portrait for the life of me I can't get it to inherit the right weapon--the glam plate it uses is has a paladin weapon on it but it's a dark knight portrait and it's constantly picking up the wrong weapon glam even if I make sure I have the right weapon glam on first before trying to edit it. No idea why I can't fix it, so I've given up on it. I'm usually pretty good at figuring out what's going on with the portraits and they've added much more informative error messages, but that one's just a lost cause.