I just started charting like a week ago so the problems I have are probably self inflicted, but I don't even understand that warning. Most of the songs I've charted don't start on the first beat and there's some silence or other noise before the music starts (nobody home for instance with chatting for 18 seconds). I've been adding 3 seconds of silence and then moving the start of the track to the first beat of actual music. My problem is this... half the time I pick YES and add beats. Sometimes that works and sometimes it doesn't. And what I mean by that is, sometimes when I say YES the music starts x seconds before the notes come down the highway and sometime it works perfectly (not accounting for OP's original problem of whether or not the 1st beat is at the start of the measure. I've tried every combination of adding silence to the MP3 and GP4 files an it's always inconsistent.