Same. Started about an hour ago for me. Tried updating devices, restarting Macbook, etc. Same message everytime. "Unable to Verify App"

For some additional context, I was able to fix this for internal testers, by deleting all of them and then re-adding. Other testers the issue still seems to be occurring.

I've had this exact issue pop up occasionally as well. Our issues have been a combination of this and what I've posted in this thread: https://developer.apple.com/forums/thread/806242

I've uploaded sysdiagnose logs to the Feedback Assistant ticket.