Has anyone else encountered this issue yet? I have a project that has been deploying fine until the Big Sur / XCode 12 upgrade. It looks like there are some new entitlements (or old ones that have been renamed) that Xcode can't retrieve from the developer portal, so although you can build a project, fastlane cant deploy it to testflight because of the error above. The prevailing "fix" seems to be (from
https://developer.apple.com/forums/thread/650490):
Install the "Transporter" app from the MacOS app store.
OPEN Xcode 11.5 archive your project
Close Xcode 11.5 -> Command + Q
Open then Xcode 12 Beta
From Xcode's organizer, select your archive and press "Distribute App"
Instead of "Upload", select "Export" and proceed as usual.
Drop the exported .ipa into the transporter and press "Deliver".
I don't know if that's the fix for Flutter apps because I still get the signing problem. Has anyone been able to make this process work?