There are a few items that have a messed up thumbnail when you try on, or just doesn’t exist all together.
The following includes:
Crazy Safari Cap - Crazy Safari Cap - Roblox
The item can be seen duplicated in R6 one on your avatar and one far away messing up the thumbnail on Try-On
Safari HeliCap - Safari HeliCap - Roblox
It’s just a missing thumbnail which can be restored easily