I'm using:
Subform 3338.0.0 19791b5
on Darwin 16.6.0
on OS Sierra version 10.12.5
and am having trouble when tabbing through the input fields in the element layout panel. If you start in the 'Spacing before' input field on the 'Cross Axis', then hit tab a few times it will only go as far as the horizontal quick align and then will begin hiding and showing the panels. It feels like normally you would expect it to tab down to the 'Main Axis'?
Video: