[PR2 Bug] Animation from Jetpack disappears sometimes

[Master Raiden]

It appears that something is causing the jetpack animation to show as a still image instead of an animation.

Here's a video of the jetpack functioning properly.
https://sendvid.com/rkiuzyya
Notice how the exhaust 'moves' and fluctuates in brightness a little bit.

Now here's a video of a buggy jetpack.
https://sendvid.com/m74kdweb
Notice how the exhaust doesn't move at all. It's just a still image now.

I've noticed that this happens in Ashley766's video (Starting at 0:12)
So the jetpack got stuck in a state where the animation never runs properly.

I was able to reproduce the buggy jetpack by jetpacking under an infinite item block for at least 1 second before moving away.
Releasing Space and holding Space again causes the jetpack animation to run properly.