yotaphone 2 eink support not working (on lolipop?)

[sophana]

Hi

I have a yotaphone 2 with eink display.
I have a menu entry : "go to back screen" (I have a french unit)
When I click on it, it says that I have to turn the device to read the book in the back screen.
But it does nothing when I turn the device.
Backscreen remains unchanged.

If I could help debugging this major feature for yotaphone users, it would be nice, but I would need some help. I can try to compile the software if needed.

Thanks!