AirDrop to iMac (2020 Intel/Ventura 13.2.1) not working since upgrading to Ventura

Thanks so much for all the tips! I have double-checked everything from your suggestions (I have my iMac set to receive from everyone, and the Firewall is not on), but the problem still persists.

It's very strange because AirDrop seems to go through every step of the transfer process except the final one of actually transferring the file. When I initiate an AirDrop transfer from another device like my iPad, my iMac appears as an available receiving device, I tap it, there's a moment while the icon displays "waiting," then the transfer proceeds with the blue ring circling the iMac icon clockwise while displaying "sending," when it's done it displays "sent," then my iMac pings to indicate it has just received a file, and it brings the Finder to the front as the active window. But when I open the Downloads folder, it is empty! As I understand it, AirDrop only sends files to the Downloads folder, right? In any case, a Spotlight Search for the missing file turns up nothing.

All of my devices are running the latest, fully-updated versions of macOS/iOS/iPadOS, and all have been rebooted a few times in case it might clear up the problem, but it hasn't helped.

Hi! Thanks for the suggestion. I just created another "test" user account, and AirDrop DOES work for it. I was able to send a file from my iPad to the "test" account on my iMac. Interestingly, when I'm logged in with the "test" iMac account, and I select AirDrop on my iPad, there are two iMacs that appear, one with the icon associated with my Apple ID, and a gray & white one presumedly for the "test" account (for which I did not enter my Apple ID). It is the gray & white iMac icon which receives the files fine.

When I return to my main user account on the iMac, AirDrop still does not work normally. HOWEVER, when I select AirDrop from the Finder sidebar (or the Go menu), I now AM able to send files to my iMac from other devices. I don't know why this began working when I created the new "test" account, as it hadn't worked before. It's certainly not the most convenient way to use AirDrop, and it isn't the way it used to work, nor is it the way it works in the "test" account, but at least I can transfer files. Clearly, as you suggest, some third party software may be interfering with normal AirDrop transfers (i.e. transfers that work anytime, regardless of which app I'm currently using, and don't require me to open up AirDrop in the Finder), but going through the process of elimination to find the offending party is not going to be worth the time, especially as I've now got a workaround solution.

Thanks so much for your help!