8bitdo micro in Switch mode

[pezbailarin]

I am using an "8bitdo micro" joystick in Nintendo Switch mode to turn pages in my Kobo Clara BW.

The device identifies itself as "Pro Controller" and works just fine.

But I cannot make the big shoulder buttons work.

$sudo evtest tells me the name of the events for those buttons

Event code 310 (BTN_TL)
Event code 311 (BTN_TR)

But I've tried these lines in my config file:
prevPage EV_KEY BTN_TL 0
prevPage EV_KEY BTN_TL 1
nextPage EV_KEY BTN_TR 1
nextPage EV_KEY BTN_TR 0
nextPage EV_KEY 311 0

and they don't do anything.

I can make any other button/event work to move pages or chapters, but not those particular ones - which would be my first choice.

What am I missing?