My work day started with my awesome new Logi MX KEYS keyboard not Bluetoothing to anything, anywhere.
I was worried I owned a nicely-weighted, space gray brick.
It’s rechargeable and therefore sealed. The power switch didn’t change anything. None of the key presses in the Quick Start guide changed its behavior. None of the forum posts addressed what I was seeing. So I went rogue. After a lot of searching for any mention of what I was seeing, I began experimenting with long key presses and multiple key combinations and finally got to where I could pair the keyboard to my Mac again.
I was able to hold the fn and F13 keys to get it into pairing mode for device 1. Then, on my MacBook, I was able to use the Bluetooth preferences in the System Settings application and subsequently the Logi Options app saw it again, as well.