Why coming back to US with AP is risky??

Hi, I recently filed I-131 after filing I-130, I-485 and I-765 a few months earlier. They started charging you $630 for I-131 and I thought I would save up money by skipping it but one of my family members in home country has been sick and I changed my mind to file it to visit them.

But I don't want to believe that many people are paranoid about traveling with AP... If there's a big change of you getting in trouble with AP, what is the point for obtaining AP by paying $630 :(

Anyone know someone who have been in trouble at the airport cuz of AP??