Airdrop connection difficulty: Mac mini, iPhone, iPad trio don't connect

I need to make Airdrop operate so that I can transfer photos to the Mac mini. But while they can all eventually connect, the Mac mini doesn't show up when I try to send a picture to the Mac mini.

Any suggestions welcome.

This is my last ditch effort: I've surfed up tons of "Airdrop connectivity issues" stuff on the web. But nothing's been successful.

At this point, I can transfer from iPad to iPhone and back. But can't send anything to the Mac mini.

Mac is running Catalina OS.