Since the release of Xcode 11.5.1, I can longer add a Swift Package Dependency. This is the case for SwiftUI and CommandLine Apps. Existing apps, that already have included Package Dependencies, continue to keep them. But I can't add any addition packages.
The "Choose Package Repository" window appears, but the Previous and Next buttons are disabled.
I've even tried reinstalling Xcode. Frankly I'm stuck. Any ideas?
SOLVED - with a sledge hammer! First, I copied all Xcode projects to an external disk and unmounted it, then I did a Command-R on reboot and ran First Aid on all 3 APFS partitions. No errors were reported.
On restart, I created a new Xcode project and "magic", I was able to add Package Dependencies once again! Perhaps it was because I'd been duplicating some of my folders contain projects - the novice way to create a branch - and that was confusing some of Xcode's undocumented and hard to find files.
The real odd thing is, Xcode is now creating an extra Tests folder for Previews (and probably other thing it didn't before). I really wish Apple would concentrate on getting CURRENT things working, including decent documentation and telling us how to create modern Help files (instead of the obsolete ones), before bringing out new Beta versions with even more bugs.