Bluetooth Setup Assistant Not Working with Big Sur 11.2

I have a Mac mini 2018 using macOS Big Sur 11.2. I have a Magic Keyboard with Numeric Keypad and a Magic Mouse 2 (both Bluetooth devices) that I frequently use with a Windows laptop. 

When this system was being used under macOS Catalina, after using the Bluetooth keyboard and mouse with the laptop and then going back to the Mac mini, the Bluetooth Assistant would open to connect the mouse and keyboard back with the Mac. The Bluetooth Assistant is supposed to open if the appropriate boxes under Preferences>Bluetooth>Advanced are checked, which they are (as shown at the bottom of the screen capture below).

Under Big Sur, this does not happen. So, my question is: Why? Or maybe more appropriately, why doesn’t the Setup Assistant open? The only way I can log onto the Mac is to plug in a USB keyboard and mouse, which is a pain and not a very elegant solution.

Does anybody have any ideas as to what I can do to get things working again?

Here is a screen shot after I manage to get back on my Mac and manually get the Bluetooth mouse and keyboard connected. The upper right shows both devices connected, yet for some reason the mouse preference dialog (in the middle) says “No mouse found.”