Help Exporting MIDI

I have not used Cubase for years, but still have SX 3.1 installed on a old Mac. I’m going through about 25 projects done in earlier versions, and for the most part I can export the Audio files and and MIDI for import into other apps, With one project, I’m getting a zero byte MIDI file. The MIDI is clear visible in parts on three tracks, can be edited, etc, Ive tried selecting it several ways, but in every case I get a zero byte file. MIDI is exporting as expected in the other project, but not in this one.

Can anyone suggest anything I might be overlooking in settings or process?

Can’t think of what that could be. The midi plays in the song?

I would select the midi on a track and copy it then open a new project and paste it in there.

Back and forth. You shouldn’t have to export the audio, it’s there in the audio folder.

Do the songs have their own folders?

Yes, MIDI plays through the included VIs in SX 3.

Songs saved in SX3 have folders. Some created in earlier versions don’t but all open in SX 3 and can then be saved as SX 3 projects. The audio opens in other DAWs without problems, so I’m just making sure all the audio parts start at the same time and using them as they are. It’s only the MIDI I have to export.

I’ll try copying to a new project.