Portion of code only works part of the time

This is the code I need help with. It is activated via a block break.

The random function and sound always work. The teleporting mechanism, however, only works about 40% of the time. It is not because I am being teleported to the same place; you can tell when that happens. I have tried:
 

• Using a random double instead of int
• Setting a higher minimum Y position

Please let me know if you have a solution. Thank you!