TIME! That's all we needed to do. The longer it sits the better it will come off. We noticed the exact same problem. More time spent peeling the backer than the rest of the install. Ridiculous. If we just apply the tape the day before it comes right off. I think it's because the VHB cures some and won't lift. We were applying it moments before the install and it almost will not work. One day makes all the difference.