Not just the PC client. I'm having the same problem in iOS. Not sure how you are supposed to make JJ stronger. Are his stats dependent on the other characters? Can anyone who has them at higher than R5 get through it?
Edit: was finally able to get through this after a million (well at least 50) attempts. The BN basic to start was a good tip, but the event sure does seem bugged. On the run that actually worked, JJB just seems invulnerable, and maul's swooshes did nothing to him... In so many of the other runs, maul just one-bangs him
Capital Games Team