Just spent all night switching over to the 4.22.0 release and I still see this error:
UATHelper: Packaging (iOS): ERROR:
UATHelper: Packaging (iOS): Unreal Plugin file Engine../…/…/…/Project/UE4-4.22.0-ios/Plugins/UniversalMobileAds/Source/UniversalMobileAds/UniversalMobileAds_UPL_IOS.xml missing!