Bummer doesn't even come close to expressing what it is actually like to go through this. I simply stopped clearing the tv and guide data/cache and don't have to keep making 650 channels hidden and/or messing about with groups. How do I avoid it? First, disable live tv in the settings menu. Next, go into the userdata/addondata folder for the pvr and delete the epg_cache.xml and also the epg11.db from the database directory. Then restart kodi and re-enable live tv again. Should be golden.
Of course, this assumes you took psycon's advice and updated the guide from the ninja installer as well.
It works for me, hope it works for you, too!