It's same issue as b/119616264. Based on the observation in b/119616264, it looks like somewhere in the middle, Chrome didn't get Bluetooth device change notification, thus didn't know the device has an available touchpad/keyboard device. Unpair and re-pair force resending the notification, thus Chrome can behave correctly. 

So it looks more like a Bluetooth flakeness issue.

Even if BT doesn't send the device change event we should know if we see the mouse moving around and the user typing.

I'm also concerned that he was able to get it into side-docked shelf even though it was stuck in tablet mode. (see attached)

Deleted: unnamed.png 637 KB

	unnamed.png 637 KB View Download

I'll take adlr@'s device and keyboard to take a look. 

Re#2: after the device is connected, typing on the keyboard or using the touchpad won't resend the bluetooth device change notification, see the kinds of changes that we monitor: https://cs.chromium.org/chromium/src/device/bluetooth/bluetooth_adapter.h?rcl=dde3e089f6933f90a6a56e6b588c87863f88a727&l=88.

I also got adlr@'s device but can't repro it anymore. 
adlr@, do you still remember any specific things you did when you had this issue?  And how did you get the side-docked shelf?

Took a look at the device with adlr@. Can't repro this issue any more. 
I'll close it for now. Feel free to reopen if you manage to repro it. Thanks.