Calendar High Sierra Issue

Added note: I looked through preferences to see if anything was different and I did turn up account delegation. After making sure I'd checked all the CalDav accounts associated with my Calendar / Email / Notes and to which I have read/write access... I restarted the apps, then system, but no luck! I still can't accept appointments to the calendar in which they belong.

Thanks Barney-15e... I've now spent quite a deal of time with elevated Apple support and it turns out that since the upgrade to High Sierra, the calendar will still work as expected invites sent to an icloud email address but not invites sent to/from gmail accounts (however, it used to work properly with gmail / google calendar accounts in all previous osX iterations). But since the upgrade to High Sierra, the function is no longer working. However, I've been told the calendar team is aware of it and that it wouldn't be unlikely that the features would return in a future update. Unfortunately, it means I have to switch to using google calendar going forward as I can't have my personal invites ending up on my work calendar. Bummer.