Apple magic mouse reverts to right-click-only mode, and becomes useless.

I have a relatively new iMac Pro with a wireless magic mouse.

Spontaneously, the mouse reverts to right-click-only mode, and becomes useless. All clicks show the right-click menu. Turning it off, waiting 15 seconds, turning it on, and waiting an interminable 30 seconds for the mouse to be recognized typically solves the problem, but is a real pain. And once, I had to shut the whole system down. Just checked the mouse battery level and it is 31%.