deleted podcasts keep coming back when synced in iTunes 12.5.4

I delete as I go when listening to podcasts using the Podcast app on iPhone 6S Plus. When I sync with iTunes 12.5.4 periodically all my deleted podcasts re-appear on my phone, but not in the Summary in the sidebar. When I go back to my App, there they all are again, sometimes going back to 2015. My podcasts are now using in excess of 1.5 GB of memory. I cannot keep deleting them one by one all over again. There is no way to delete them in bulk. In iTunes these add backs do not show. There does not seem to be a fix for this. Once before I had to completely reboot my phone with a tech person, after a total of 4 hours on the phone with him. 5 days ago I synced my new iPad Air 2 via iCloud and the problem returned. Please help me!