I uploaded an animated UGC accessory (flying bats). In Studio and in-game, everything looks correct.
But on the Roblox catalog/website, the thumbnail preview is broken — the item is either invisible.
This only happens on the website preview; the item itself works fine.
I took a look at the item, and the UGC thumbnail is showing up fine for me. It doesn’t seem like there’s an issue with the item itself, so it might just be a bug on your end or something temporary.
This is a problem with our 3d thumbnail generation - we don’t have a timeline for fix but we are working on it and know that this is a problem for certain assets / animations!