Hello guys and thanks for your replies !
Just to clear things up a little, i am indeed aware of how the whole thing functions as i'm a "heavy" glamour user. The weirdest thing is even that i have a couple glamour plates from last year that use some items from the armoire (like earrings from seasonal events and such), and i'm still perfectly able to apply these to my gear.
For some reason it just seems that i can't get the armoire items to display when i want to create a new glamour plate, which makes them effectively useless.

As i said i tried to withdraw them into my inventory, then put them back into the armoire, but that didn't change anything. Restarting the game didn't have any effect either.

I suspect that changing DC might have something to do with it, which is why i'd like someone from SE to look into it ^^'