[2021] Ropalolyst fight bug: impossible to complete in Steel Path, workaround for normal

We've tried this multiple times and never got "When it comes to phase 3, the ropalolyst starts throwing itself off the platform"  to happen. Is there some missing ingredient that you could help us with? Did somebody get knocked off the Ropa, are you doing anything with mind control or crowd control?  There shouldn't be a reason for it to try stepping off the platform, which is where it's going off the rails.