And I’m using grid for the bottom section (below the slider), but the grid isn’t displaying in the preview or live - just portions of it. I’m not sure if I’ve set something up wrong or if this is a bug?
Your placeholders only have the min-height value set in designer. In the published source, that value is not present.
The min-heightCSS property sets the minimum height of an element. It prevents the used value of the height property from becoming smaller than the value specified for min-height .
Inspecting the source on the published site, shows the Grid is defined and present. The rows are collapsing since there is no element with a height value. Try assigning height to the placeholderdiv class.