I’m having the same problem, however the “On refresh, preserve previously imported events that are missing from the feed” option is not checked.
I believe my setup is the same as pnaw10’s – I’m using the All-in-One Event Calendar by Time.ly plugin to import an ICS feed (Actually, it’s seven different ICS feeds).
That option is not check on any of them. However, when I delete events from the google calendar, they don’t delete from the feed on my website.
Anything else I can try?
Thanks!