I just encountered the same problem. Shortly after we crossed the bridges with lightning, and were headed up the slope towards the final boss, Keil just stopped right near the top of the slope, just before the forcefield doorway, and wouldn’t move. We tried talking to her, returning to a waypoint, using swiftness buffs on her, and nothing worked. She just continued to stand there, and unfortunately we had to disband the group and give up, since there was nothing else we could do.