there appears to be a bug with this that you get when you hit PSE Burst on the acquisition of your 5th token for the "Rappy Meter".
Scenario : your Rappy Meter is 4/5 and you hit 3 Rainbow icons. this not only makes Rappy Meter full at 5/5 but also activates PSE Burst.
now... the bug is that when PSE Burst is finished you longer have your full Rappy Meter.
so, you fill Rappy Meter to 5/5 and this gives you a chance to lock in the center space to a Rainbow icon. which gives you better chance to hit PSE Burst. now... lets say you hit PSE Burst on your first spin, leaving your Rappy Meter at 4/5. once finished with PSE Burst you will go back to normal play not having the center locked in anymore. big thing here is that, NORMALLY, you would go back to normal play with 4/5 Rappy Meter still.
i don't know if what happened to me was normal, or is a bug. but i would say you should have at least the 4/5 Rappy Meter after hitting PSE Burst under such a condition.