Audio stretch not working properly

[ThexEmperorx]

I have a song with a bunch of eight notes at a really fast tempo, and I want to make the song twice as slow and replace the eight notes with sixteenth notes. I used the audiostretch tool to stretch the song by 50%, but when I try to shrink the MIDI region, it also slowly deletes notes at the end as I shrink it. I got rid of this by adding extra note at the end after my song, so those extra notes get deleted instead, but the notes still don't line up after I shrink it by 50%. I used the final note of my song, which is on beat 1 of measure 257, as a reference note. The note should end up starting on measure 129, one more than half of 256, after I shrink it (and my midi region does start at the first beat of measure 1). But after I audiostretched it by 50%, the note doesn't line up where it should. After experimenting with the audiostretch tool, I think it has to do with the fact that when it audiostretches, it also deletes the notes towards the end, but I don't really know exactly why. Am I doing something wrong, or can someone explain to me why this happens?