Import or have midi data in metro
goto FILE / Export midi file....
choose either type 0 or type 1 (doesn't matter which)
save it
Get info - document created is 4k on disk (54 bytes) and does not play
(is it zero in length and the 54 bytes is the icon or something?)
Using 10.2.6 and Metro 6.3.2.1
NOT a problem in 6.3.1.1 which tested just fine I'm sorry to say.