I have a command line tool that zsh refuses to run when built for Apple Silicon or as a univerisal binary (the specific message is zsh: killed TOOL_NAME). I can only get it to run if I build it exclusively for Intel/Rosetta. Running/debugging from within Xcode works fine for any architecture. The tool is a very simple C/C++ unix command-line tool; it doesn't have any external dependencies beyond the C runtime and the C++ STL. I suspect something in code signing is going awry, but I've tried various team and certificate combinations without any luck. I've also tried enabling/disabling the app sandbox, also without any luck. (The app is not for distribution so it doesn't really need to be code signed at all.) Any suggestions?

I just upgraded to Big Sur and now I can't resize the navigator pane in Xcode 12.3--a major problem when a project has a directory structure deeper than two levels. Other apps (Finder, Safari) don't seem affected. More information: Not all projects/workspaces are affected. The project that was is one generated using cmake, and re-generating that project has fixed the problem.