I'm having the same problem. A search has found this suggestion: "The problem is resolved by switching to posix_spawn()" I haven't tried it yet.

I found the answer: there was a User-Defined value for VALID_ARCHS which was set to x86_64. I added arm64 to this, and I'm now running my app as Apple Silicon natively.

At the top, is says this ... ... and the "My Mac" (without Rosetta) option is grayed-out. Does that mean that it thinks my machine is Intel-based?

I made that change. It still builds, but when I try to run it, I get the message "A build only device cannot be used to run this target."