If you're not time critical, you could do a factory reset to see if that clears the
bug: BUT THIS WILL DELETE EVERYTHING ON THE
CONSOLE AND RESET IT TO FACTORY SETTINGS. Turn it off, hold 789 down while you turn it on, then turn off and on again. Then reload your show file (or one that you know works).
Or +1 for calling tech support. They really are the best, even for legacy products.