It doesn’t give that option likely because the container it is in is fixed…not 100% sure as this is all pretty new stuff.
Based on the settings of that Icon I would look at the settings of the container to see why the container is collapsing.
If the settings on the container are not such that it would collapse, or the container is not collapsing I would send a Bug Report.
One way to test if the container is collapsing is to put a background color and preview the page. If you see it, it is not collapsing.