iOS Question OTA deployer issue

Hi everyone,
porting my App from Android to iOS went well, but now I spent the full day trying to
make the App available to my beta testers. I was following the guidelines here.
The App gets uploaded, but at final MBs the OTA deployer always throws this
error message, which relates to HTTP error 500 invalid user ID:



I assume user ID refers to the field Account ID?
Account ID is actually what is called Teams ID in the developer account Membership details?



Any help would be highly appreciated!

Thanks