"Add Background" button not appearing

Hey all, I'm using Teams on my 2017 Macbook Pro running Catalina v10.15.6, trying to add custom backgrounds to my calls. In the past I've been able to use any image as a background, however, the + button isn't appearing at all as of recently. Is there any way I can get it back? I've tried adding photos to the Uploads folder, but nothing in the said folder even shows in my background selection. Any advice?

Thank you in advance!