Design

if all of the elements are actually in the frame (you mean figma frame right?)

Then when you export that it would all be there.

If there are elements that aren't actually within the frame or its sub groups they won't export 

But quickie hack is just draw a selection over the lot and copy as png

Yeah when you click on the title of the frame you will see all the elements in the layer side bar

Its super ez for something to be "on top" of a frame and not actually in the frame, you can just click on the elements and drag the layer item into the group/frame section to make sure its all in there