When using flow. They keyboard take longer or in some cases does not follow the device the mouse has switched to.

For example. I was on PC1 then I moved my mouse towards PC2. The mouse moved to PC2 but the keyboard was still connected to PC1. The the keyboard to move to PC2 the mx master 3 mouse needed to go back to PC1 then back to PC2. Or manually change using the device switch keys on the mx keys