If you have an IP set outside of the US (Specifically most of Europe in my testing), then many studio features completely break, such as being unable to run studio test, and being unable to upload assets to Roblox.
I’ve experienced this issue myself if I set a VPN outside of the US, and my international developers have also had the issue, and must buy and set VPNs to the US in order to properly run studio.
No errors show up, things simply endlessly load, such as white-screening when you try to upload an animation, or endlessly loading when you try to test in studio.
Specifically, I know that any IP in the Czech Republic will certainly break, and many other locations as well, though that’s where most my testing has been.