Question: Using XCode 12.0.1 or 12.1 on MacOS 10.15.7 on a MacBook Pro, I cannot get my Mac OS application to compile for the arm64 architecture (i.e. make a Universal application). My project has evolved through many many many XCode versions, so I thought maybe it was corrupted somehow.

So, I created a new non-document-based app project in XCode. I then edited the scheme for Run to build for Release. The default build settings included the arm64 archtecture, and "Build Active Archtecture Only" set to NO for Release. I then set the tool bar scheme setting to buid for "Any Mac", built the project and looked at the build log. It built only for the x86\_64 architecture.

Apple's documentaton says it should build for both architectures with these settings. What am I missing?

Answer: 
The problem is Apple's documentation, whoch clearly says XCode 12 builds universal. It does not, as of this writing, you MUST use the xcode 12 BETA.
I've had older Xcode-Projects that just wouldn't build universal binaries. It was due to a VALID\_ARCHS user defined variable in one of the build settings (at the very bottom of the list). Once removed, universal binaries were created.