This is because Maple does not use global tempo, which 3MLE and Mabi do. If there is a tempo change somewhere else in the track, you have to make it match on all the tracks. This can be fairly tedious depending on how many tracks there are, and how many changes there are. It can also involve editing notes and rests to make sure the tempo goes exactly where it needs to be. This is what the Tick Step Event box is for. It will tell you exactly where everything is. So if there is a tempo change at 78.0192 (which basically means measure 78 at the halfway mark), then there needs to be a tempo change across all tracks at 78.0192.