Finally found the issue this morning. While comparing the project configuration with another project, I noticed we were excluding the arm64 architecture. This was done at the time because a dependency was not (yet) supporting it. I removed the exclusion, compiled with no problems and the tests coverage is back! I guess internally Xcode 16 expects the arm64 architecture to be supported.

Yes @wilmar, I do. This is indeed the source of the issue.

I I use the xcode-select command, then on next xcodebuild I get: xcode-select: error: tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance