Gamepad D-pad mappings don't work

My phone: Huawei Nexus 6P

This is a big issue. When pairing a PS3 or PS4 controller (using SixAxisPairTool. The controller is seen by Android as a native gamepad), ALL button mappings work perfectly, with the exception of d-pad left/right.

I'm trying to use d-pad left and right to move left and right in the inventory row at the bottom. Problem is, when I hit LEFT, the selection box will only move 1 box to the RIGHT, but no further.

Same thing with hitting right, which makes it move 1 box to the left.

Hitting down/right at the same time will move consistently to the right. But unable to use that similar glitch to move left. Any use of the dpad-up activates whatever is mapped to UP only.

Same exact behavior is present even in the full screen blocks selection window