New (refurbished) iMac, can't open Safari windows after setup

I purchased a refurbished 2017 iMac 27" from Amazon. It is running Catalina. I used the setup assistant to migrate everything from my 2011 Mac Mini running High Sierra. I can start Safari, but it will not open any windows. I click New Window, and nothing happens. It pulled over my browsing history, but not bookmarks (same for my wife's user account). Everything else, including other browsers, seems fine so far. I did erase and reinstall OS X, and run setup assistant again, but it's still the same results. Any ideas? Thanks!