+1 This seems to be a regression in Xcode 12.5; it works fine for me on Xcode 12.4, and is grayed out in 12.5. Running a unit test on an iPhone simulator in my case. I filed feedback: FB9116191

Hey there Jason, thanks. We distribute our iPhone, iPad, and Watch app on the iOS App Store, and the article suggests it should be possible to reset the build number to 1 while bumping the version number: Apps for [iOS, watchOS] platforms can use a lower build number for a new version compared to a previous version because App Store Connect requires each app version to use a unique combination of CFBundleShortVersionStringand CFBundleVersion. However, Mac apps must follow different build number requirements. To successfully submit a Mac app to app review, its build number must continuously increase, even across app versions. The app is Apple Silicon Mac-compatible, and we do not opt out of distributing it on the Mac App Store as well. However, it does not have a Mac target (no Catalyst). Does that limit us from resetting the build number? If we hypothetically opted out of distributing on the Mac App Store, would resetting the build number work as expected?

It's a shift from how we were doing things, but I see how it should work from now on. Thanks Jason.