I always do a manual cache clean after a reboot to. Keeps it ticking along nicely.
your timeshift setting is correct to disable. You should still be able to pause then fast forward and then rewind. but you shouldn't be able to just rewind as it doesn't start saving until you pause.
I have restarted it still does not show up in the list of plugin installed. I have no issues without it any way i am using a usb stick for buffering not the internal memory.