I had the same issue since updating to Xcode 12.5. However, what I discovered is opened Swift packages loop on resolving if you use a relative location for DerivedData. Try opening Xcode 12.5 preferences go to Locations and set DerivedData to default location. Problem went away for me. This is a less destructive way to solve this problem rather than deleting Xcode configuration.
Topic:
Developer Tools & Services
SubTopic:
Xcode
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