Midi on Mojave

might be worth posting on a logic forum, such as: https://discussions.apple.com/community/professional_applications/logic_pro

 

Why do you think the problem is MIDI related? Are your speakers connected through MIDI?
If you select your internal speaker for the audio output, can you hear any sound?
Can you hear any other system sounds?

 

Try create a new MIDI AU and drag the MIDI data to that stem. Does it now play?

Also try just playing anything with the musical keyboard (CMD + K) in a fresh stem. Anything there?

--- Post Merged, Oct 25, 2018 ---

Also do you use a DAC? The audio default might still be set for that.

 

I'm on Mojave, running latest Logic with an older Apogee Duet FW, and 2 midi USB devices: iRig keyboard and Logidy foot controller, all with no issues.

 

Also OP, are you on Logic 10.4.2? I'm running that on Mojave with no issues.

I've seen occasional problems with MIDI before but it's literally just a case of creating a new track to troubleshoot.