Trying to learn why the File > Export > MIDI File... command doesn't work for exporting my entire project as a MIDI file in FL Studio v24.1.2 build 4430; when I try to export the MIDI file, the export completes successfully without error but the MIDI file is always empty. I'm running FL Studio under WINE, so I thought it might be due to that, but first I looked it up on a search engine and found this result from Reddit:

QuattroMusic @ /r/FL_Studio:
If you go to the tools > macros > prepare for midi export, it should work then. Remember to save the project first, by doing this it will delete all the sounds.

Tip: if you just want to export a midi pattern, go to the piano roll > arrow on the top left > file > export as midi file

Tools > Macros > Prepare for MIDI export appears to turn every instrument into a MIDI Out instrument and it cannot be undone. After this step, the export command now works. This is kind of terrifying because i save compulsively, so I should probably save the project as a new version with File > Save new version before doing this, otherwise I might write over my project with a version that cannot produce any sounds.