I've frequently had this problem when connecting my Logitech K480 keyboard to my ThinkPad X1. Often when the laptop wakes from a low-power state, either hibernation or sleep, the keyboard won't reconnect, and the only solution is to reboot.
I've frequently had this problem when connecting my Logitech K480 keyboard to my ThinkPad X1. Often when the laptop wakes from a low-power state, either hibernation or sleep, the keyboard won't reconnect, and the only solution is to reboot.