Description of the issue

When using a VerticalGridView with a ConcatAdapter, the focus jumps when passing from an element from one sub-adapter to an element from the other sub-adapter.

E.g.:

Adapter 1 = 2 elements
Adapter 2 = 15 elements

Focus is on element 0 (Element 0 of Adapter 1)
I press the DPAD down
Focus is on element 1 (Element 1 of Adapter 1)
I press the DPAD down
Focus is on element 4 (Element 2 of Adapter 2)
I press the DPAD up
Focus is on element 3 (Element 1 of Adapter 2)
I press the DPAD up
Focus is on element 2 (Element 0 of Adapter 2)
I press the DPAD up
Focus is on element 0 (Element 0 of Adapter 1)

A recording of this can be found here: ConcatAdapter_bug_on_Android_TV.mp4.

Component used

LeanBack: 1.1.0-alpha04 (I had the same behavior with 1.0.0 though)
RecyclerView: 1.2.0-alpha05

Devices/Android versions reproduced on

Any Android TV

Sample project

https://gist.github.com/bmonjoie/6ceb2965834bc22ef78be8ca8ddae969