Playing on Lumia 950XL, updated to the last available OS version 10.0.15254.1.
Playing both in phone and continuum mode.
Playing with the XBox One S controller (original Microsoft).

Defect: when pressing the B button opens the menu even when there is a dedicated button to do that, then the HUD disappear.
Premise: the controls are reset to default.

How to reproduce the defect:

• Pressing the B button of the controller while in game to crouch opens the menu.
• Pressing the B button and keeping it pressed, when released opens the menu, closing the menu makes the HUD to disappear and the first object in the hotbar to be dropped repeatedly, pressing B again makes the game return at the title screen (rotating background) without any UI (no menu, no way to go back).
• Pressing the B button while the inventory is opened closes the inventory and hides the HUD, if pressed again 2 times makes the game return at the title screen (rotating background) without any UI (no menu, no way to go back).

Regaining control of the game in touch mode shows the touch controls but not the rest of the HUD.