MULTI TRACK PLAYBACK ISSUES

I don’t use the midi feature – but have you tried to put a midi event right at the end of your midi file? Logic may be seeing that there is no more information after ‘x’ amount of time and truncating the file?
If that’s not the case maybe take a closer look at the midi file in logic and make sure there isn’t an event that causes the problem around 8 seconds in…(anything that differs from you other midi files that are working correctly…