New problem with korganizer and google calendar: local changes do not get saved

After lots of problems over months/years with korganizer properly accessing my Google calendar, it was working fine for several months. However, I recently discovered a new problem (at least new for me.) I have an recurring event which was originally created in Google calendar, not korganizer. korganizer sees it fine. It was created for eight weeks. However, some of the eight sessions have been cancelled. If I delete the single events in korganizer, as soon as I refresh or restart the Google calendar, the all reappear. Am I missing something I need to do to push changes up to Google for them to stick?