Facebook events not properly syncing in Apple Calendar

Yes, I know that Mojave removed Facebook integration from the System’s "Internet Accounts”, but supposedly, subscribing to Facebook events is still possible. However, I find that it doesn’t work as it used to. In particular, I still see a lot of FB events in my Calendar that I have been invited to but that I marked as “Can’t go” in FB. These used to disappear from my Apple Calendar, as they should.

I tried to solve the issue by setting up the subscription from scratch (by clicking on “Upcoming Events”). This new file was duly imported into Apple Calendar, but as far as I can see, only one single event actually shows up there (the first one coming up as of today that I had marked as “Going”).

Clicking “Calendar info…” for both feeds propels me to System Preferences’ “Internet Accounts” with iCloud (the first option) is selected…

What is going on? and is there any remedy?

Thank you,
Albrecht