Running locally gives an error that "Another instance of SwiftPM is already running"

[helloITdepartment]

Running swift package --disable-sandbox vercel dev outputs a list of packages, updating, computing, creating working copies

Then says

Building application
-------------------------------------------------------------------------


/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift build --package-path /Users/.../hello

 Another instance of SwiftPM is already running using '/Users/.../hello/.build', waiting until that process has finished execution...```

And never continues, as seemingly it itself started the other instance (they both show up in Activity Monitor when running the command)