Created account just to chime in on this. This feature should have been built in, right out of the box for this combo! The Flow feature is way too finicky and a simple device switch should be done inside the devices and not rely on installed software. The MX Keys (and Mini) and MX Master 3 is a great combo, but manually having to mess with the buttons on both the keyboard AND mouse every time you want to switch devices is annoying!
Created account just to chime in on this. This feature should have been built in, right out of the box for this combo! The Flow feature is way too finicky and a simple device switch should be done inside the devices and not rely on installed software. The MX Keys (and Mini) and MX Master 3 is a great combo, but manually having to mess with the buttons on both the keyboard AND mouse every time you want to switch devices is annoying!