I can't seem to figure out how to upload any GIF files successfully to the forum. I have tried the insert button at the bottom of the Thread/message editor and the upload button in my Files tab of my account, and I can select an image(I have a GIF from Pico8) in the popup and press the upload button, but it never appears in my uploaded files. What am I doing wrong? Thanks!

Personally, seeing as you get very limited upload space on this site (and especially considering GIF export from Pico-8 can be rather large!), I'd suggest using an image hosting site like Imgur and link directly to it.