Forticlient error: "Internal error. VPN status observer is already set."

I'm trying to get my work VPN working on a new Mac Mini (M1, 2021) running Mac OS 12.6. When I try to connect with Forticlient free VPN software, I am asked for the token digits and can get through that, but then I get a message: "Internal error. VPN status observer is already set."

This does not happen on my 2015 MacBook Pro also running Mac OS 12.6. So it's not an operating system problem. I also did a reinstall of Mac OS on the new Mac Mini and that did not fix the problem. Also, since I can access the VPN using the MacBook Pro and my iPad, the issue is not my personal account.

Anyone else see this message and know what it could be about?

One potential clue: in setting up the Mac Mini, I used Migration Assistant to transfer data from a 2013 iMac running Catalina. It's possible some bad files are buried in the system--any suggestions for a good uninstaller (better than the Fortinet uninstaller) or what should be deleted?