Well this is going to sound weird but in the event that it might help someone, I am going to put it out there.
I am taking Prevacid and was always experiencing breakthrough acid. Many times a day. I accidentally discovered this phenomena when I ran out of probiotics. When I didn't take them for a couple of days, my breakthrough acid didn't happen. The Prevacid worked wonderful, just like I didn't have any acid reflux at all. So, I went back on the probiotic and then again, I started having breakthrough acid that was really irritating. So to test my theory, I stopped taking the probiotic again and I didn't have any breakthrough acid. I've been off the probiotics for three days and the medicine is working fantastic, just like it should, it's stopping the acid completely.
I don't know what the connection is but for me, for whatever reason, the probiotic interferes with the medicine working correctly. I don't know if this would happen for anyone else but I thought I should at least let you know.