We have been mixing down a song, and every single time we mix it down to MP3, the final file misses out the first MIDI drum beat. We extended that particular MIDI file backwards a full measure as compensation but it didn’t make a difference. Our WAV mix was OK, so we converted the WAV to MP3 but this is a really odd and troublesome bug. The beat also fails to appear on random occasions when we play the song in real time on Cubase. (PS: We tried mixing down in real time but our computer had a CPU overload.) Hopefully Steinberg can fix this; it’s nothing on our end.
Since you say “This is for Steinberg:” I just want to point out that you should open a ticket for this in your Steinberg account. The forums are more of a user-to-user thing, though SB staff does participate occasionally.