Scene Gallery Config buttons not working

[Dreadmook]

I'm having trouble getting started. When I open the Scene Gallery Config, I can create a new Art Tile and Frame Tile (in the Config window), but the little + buttons to create tile objects on the canvas don't seem to do anything. Holding alt doesn't make anything show up, and box selecting the entire canvas doesn't find any tiles.

Also, none of the three icons in the upper right of the window (the "Open JTCS Art Gallery Settings" cog, "Share URL" box, and "Fade Application" eye) seem to work, either.

I've tried this without any other mods active, both in my own test scene and the premade scenes in the compendium, in both Chrome (my normal browser) and Edge (clean, no extensions).

Foundry v10.303

Any ideas? Could it be a server issue somehow? Thanks in advance!