Hi Bailey, I have a similiar problem for 2 days and I just figured out how to solve it…I think it will correct yours too…At least I’ll give you what I did for me and it worked.
My problem was: when I was attempting to sell an item on the TP, the window selling menu, got only the grey background an with the search bar on the top (smiliar to yours).
After 2 tickets I was hopping that they fix with the patch but no, so after some time checking posts in forum I found this:
https://forum-en.gw2archive.eu/forum/support/bugs/TP-only-works-if-I-run-as-administrator
Basically you have to locate your Temp folder(it is in your Local folder if you use Windows 7) and then delete the folder: gw2cache-{xxxxxxxx-xxxxxxxxx-xxxx-xxxxxxxxxxxx}.
After that I ran Gw2 as Administrator… I tried to sell and I got it everything to normal.
Again this is what I did for my problem, dunno if it is going to work with you…
Hope it does
Cheers