I am also experiencing the same issue on my side, got an app that usually thanks around 10-20 minutes to process on TestFlight and it has been processing for a few hours now as well. Would be great if this was improved but at least I'm happy to read the application does process eventually.

I have experienced this running xCode v13.3 and iOS 15.4 in a React Native app. Clipboard functionality works normally in the machine it self but it cannot be pasted in the emulator as expected. I'm unsure of what's causing it but given this started happening after an update to xCode it could be that a fix is required.