I tried installing the Yamaha MX Remote Editor app on my new MacBook M1 Pro, and though the installation and everything seems to go alright, the app isn't able to find any MIDI ports that are available, including my connected MX61. Midi monitors show clearly that I have several MIDI ports available, but none show up in the Remote Editor. I suspect there is something blocking the app from accessing MIDI.
Are there any plans for an update on this app? Or are there any third party apps that can achieve the same?
We assume you have downloaded and installed the Yamaha Steinberg USB Driver for your new MacBook M1 Pro (probably the cause of your trouble - sorry I have no experience with the new Macs and MIDI)
The MX has five MIDI Ports - when properly installed the driver will find Port 5 for communication.
Link -- Official MX Download page