We are publishing SuperCollider 3.12.2-rc1, a release candidate for the next bugfix update. As this is a release candidate, it is meant for testing and evaluation, and it is not an official release. If no major issues are found in the release candidate, a proper release will be made in about a week. You can download it here: https://github.com/supercollider/supercollider/releases/tag/Version-3.12.2-rc1
This version reverses changes made to MIDI implementation on macOS introduced in 3.12.0, which turned out to introduce other issues with MIDI.