Even when you turn off the HUD in-game, the HUD is still supposed to display when the inventory is open (this works correctly with the water/food/temp/blood/health icons) however when doing this the stamina bar is missing, only the soft skills bar is present in the bottom left.

Image #1 - The stamina bar is present (HUD enabled)

Image #2 - Stamina bar is missing but everything else is displayed correctly (HUD disabled)