The layout of these two columns is messed up. While it looks good on desktop (it's 62%/38% layout), it totally screwed on tablet (it's 100%/null layout, which is rendered as 100%/38%).

Updating optimize builder to new version should fix this problem, as well as the problem with "unable to resize columns" (follow instructions on right column)...

This is just a placeholder image:

Dropping new row with two columns below arrow will render columns without resize handle in firefox browser...