I am facing issue since morning as below Error Analyzing App Version
It is seem issue from apple side. https://developer.apple.com/forums/thread/705599#705599021
This is definitely an Apple issue. You may also get an error referring to rate limiting if you try to export from the command line using xcodebuild instead.
Workaround I saw on the Apple forums was to turn off Wi-Fi temporarily https://developer.apple.com/forums/thread/705599?answerId=712953022#712953022