Airdrop hangs on "Waiting", never sends

I'd like to send a file (i.e. a photo) from my iPhone to my Macbook Pro. When I bring up the sharing options, I can see my MBP listed, but when I tap it, either nothing happens or I see "Waiting", but nothing is ever sent.

I've tried all the troubleshooting advice I'm able to find; I've reset and restarted everything, but I end up with the exact same issue regardless.

Thanks for your help!