With build 5.1.0.2822 if i select a certain amount of tracks in a playlist, say it has "33 tracks" mm will start scanning a completely different amount of tracks "297 tracks" where i only selected 33. Like in the screenshot

Second Screenshot "20 tracks" selected, scanning 297 tracks.

I sent debug with support ticket #6490.
Oh and with the debug version when i close it, it crashes. i sent 2 crash reports.