Hi Z.
My guess is to why this happens is there is some optimization that doesn't translate across MacOS versions. That's based on similar kinds of issues with illegal instructions on differing versions. We could compile these particular programs with no optimization or... we could compile for the more current MacOS. More recent OS's can also require code signing which we still don't do. One good solution then is to make scripts that do the building for you. That should be available soon. Hopefully. In the meantime, would the binaries for those two programs be okay as is? Can you build AFNI for your own system?