If you ride a piston flying machine, you'll slowly get shoved to the end of the machine. Additionally, if you try jumping while riding one, it can sometimes "suck" you back down. View the attached videos to see what I mean.

Steps to Reproduce:
1. Make a Piston Flying Machine similar to the video attached
2. Ride on the solid blocks of the machine (e.g. not slime) in any gamemode

Observed Results:
The rider is slowly shoved to the front of the Flying Machine. And, if you jump, it can sometimes "push" you back down.

Expected Results:
The rider should stay on the same block they're riding and shouldn't encounter any glitches while jumping.