This problem happens when xcode-select developer directory was pointing to /Library/Developer/CommandLineTools, when a full regular XCode was required (happens when CLT are installed after XCode)

Solution:

Install Xcode (get it from https://developer.apple.com/xcode/) if you don't have it yet.
Accept the Terms and Conditions.
Ensure Xcode app is in the /Applications directory (NOT /Users/{user}/Applications).
Point xcode-select to the Xcode app Developer directory using the following command:
sudo xcode-select -s /Applications/Xcode.app/Contents/Developer
Note: Make sure your Xcode app path is correct.

Xcode: /Applications/Xcode.app/Contents/Developer
Xcode-beta: /Applications/Xcode-beta.app/Contents/Developer