While this doesn´t solve your resolution issues it´s way faster to use the Pallette:
Select Arrange and Arrange (long)
Grab the dotted bar and dock the Arrange Bar against the Lightburn Window border
Dock the Pallet Bar next to the Arrange Bar
Grab the Pallet dotted bar and push the Arrange Bar until it ≈aligns with the right border of the Create Tools Toolbar.
Now you have Arrange (long) Bar in his place, one more place to easily check Group/Ungroup and a faster way to use Lightburn.