Found a couple of issues changing resolution in the Visual menu.
1) Clicking on the resolution makes the other options in the menu disappear.
2) After confirming it seems to break confirmation sometimes. I.e. when trying to click "Save & Close" the popup confirmation appears for a split second and disappears without you being able to select Keep. It breaks randomly, once after changing the resolution one time, the next after changing it several. Restarting the game then the popup works correctly.
Native resolution widescreen 3440 x 1440
Edit - Restarting the game works as a workaround