Keyboard is disabled on Lenovo Yoga 12 in tablet mode.

I have a Lenovo Yoga 12 Convertible Notebook. After upgrade to Leap 15.2 the following annoying phenomenon takes place.
In tablet mode (when the lid is inverted to the the back) the builtin keyboard is not working. There are some keys that are available in the tablet mode (on the lid and on the sides), and I have them bound to something, so this is not a desired behavior for me.
xinput reports keyboard as enabled. Neither xinput test nor **xev **report any keypresses.

I run FVWM on X. The behavior does not depend on the WM, so it’s something in X.

How do I disable this?