Page jumps when sticky header plugin is activated

Great plugin, but I’m having an issue. I have the effect set to activate at 300px. At that point, the new header appears and the page jumps up. It’s as if the original header is being set to “display:none” which causes the page content to move.

Is there any way to prevent this from happening? I’ve tried turning on “transparent header”, which pushes content behind the header, and then adding a new section that acts as it’s background by adjusting the z-index. This works ok, but there are two lengths of header that jumps down to one when the page fully loads.