How can I delete a family sharing request that I can't respond to?

My father attempted to set up family sharing with me so I could use his Apple+ TV login. He lives in the US and I currently live in Australia, so it would not allow us to create family sharing in different regions. Now on my Mac, there is a notification badge on my System Preferences that I can't get rid of. When I go into my System Preferences, I see there is an invitation from my father to join family sharing still pending. I had attempted to accept previously on my iPhone when it would not allow it and the notification on my phone went away. Now on my MacBook, when I click View Invitation in System Preferences, it pops up with "There was an unexpected error" which I have to click 4-5 times before it will close. It then shows a blank prompt with Decline and Accept, but no matter how many times I click either option, nothing happens. I contacted Apple Support, and they said I would need the person who initiated family sharing (my father) to follow the steps here: https://support.apple.com/en-au/HT201081. When he tried to remove me, he said he is getting a message that says “invitation sent." When he clicks into that, he gets a message saying this invitation no longer valid, and there is no option to remove someone from family sharing.

How can I make this invitation notification go away?