This is likely happening because the hiding of your ceiling occurred in the nested layer. To unhide it, click into the tile where your ceilings are and go to Edit>Unhide>All. This should bring your ceilings back, although note, that you’ll have to repeat this process for each nested element that was hidden.
Another way to check and see if you have lingering hidden geometry is to go to View>Hidden Geometry. This should show anything that was placed under hidden within your nested layers (geometry will appear to be ghosted and dashed until you click into the respective layer and ‘unhide’ the geometry.
Hope that helps!