CORS Issue when trying to access certain rooms (using the public beta server)

Guys I am having a hard time figuring something out.

I am trying to access a specific room (from FoundryVTT) but get a CORS Error here:

If I just create a new room (by adding an x or something else) it works just fine:

nothing drastic but I am wondering what messed this room up? Maybe loadbalanced to server with a different config?

Best F-