A bit of an odd situation that I'm not 100% sure is a glitch, but so far the only game I follow that I can see a custom theme on is NieR : Automata. I've tried to set Zolg and Besiege's themes, however it seems to have saved all the old theme aspects, and just wont display them. The same goes for my profile.

Any advice is welcome. I do use dark mode if that impacts anything.

You have to set a theme colour for backgrounds and such to show up.