Here’s what I’m doing:

I go into song mode.
I go to UTILITY => MIDI => SYNC and set MIDI Sync: external
I press record.
I press play on my PC, which broadcasts MIDI messages to the MOX, playing a song with lots of tempo changes.
While recording, everything sounds perfect, all the notes are played with the correct tempo changes as my PC is controlling the sync. It also broadcasts tempo change messages (FF 51 03 XX XX XX).
I press stop on my PC.
I go to UTILITY => MIDI => SYNC and set MIDI Sync: internal
The MOX now changes the tempo of the song to the average of the recorded data.
I check the tempo track and nothing has been recorded.
I press play on the MOX. All the notes are correct, but no tempo changes have been recorded, so the entire song is played back at constant tempo.

Since I’ve spent all day I’m this, I’m guessing the answer will start with: “This will never work, because...”

If that is the case, how do you do it? How do you transmit tempo changes through MIDI to the MOX in song mode, so it records them and is later able to play back the song with the correct tempo changes when I unplug it from the PC and ask it to use internal sync?

Thank you very much for your time.

The best way to transfer MIDI data from one sequencer to another is the Standard MIDI File (for several reasons) one of which is it would include the TEMPO CHANGE events, if any.

Try exporting your MIDI sequence to a USB stick as a SMF (Standard MIDI File) (.MID) when you load this to the MOX it should load the tempo changes. Let us know.

Thank you very much for your reply. :)

I can’t imagine there is no way to record MIDI input with tempo changes, but if you don’t know how to do it, then chances are no one does. :(

Anyway, I tested and it does recognize tempo changes from MIDI files, so at least I can use that. :)