I have experienced many instances of schedulers promising bonuses that did not show up on the actual assignments. Most of the time, those were oversights/mistakes and were corrected after I contacted the schedulers. There were some instances of bait-and-switch and other funny business. I did not do those shops and those schedulers went on my bad list.
If an assignment had a bonus and then someone removed it, I would do much more than not perform the assignment.