Exporting MIDI plus Audio as MP3

Apologies if this has been asked before, I did search on the forum and user manual, but couldn’t find an answer.

I am trying to export a song with MIDI backing and audio vocals as an MP3. I am making sure all tracks are selected, yet whatever I do, the MP3 is recording as just vocals (no music from the MIDI track). Any ideas?

PS I’m on Windows 10 and Audacity 2.4.2 if that makes any difference?

Audacity can’t render MIDI to audio so you’ll need to make an [u]audio recording[/u] of the MIDI, which you can later mix with the vocals.