Collapse margin + fixed margin left not working?

Do you have a bumper group underneath that floating group, that gets hidden by a responsive condition?

If not, I’d set it up like that. A bumper group Aligned Left, and the main group Aligned left as well. Then stick the floating group above the bumper group. When page is < px collapse the bumper group by setting the hiding rule in the responsive editor. And at the same time, hide the floating group.