When I open up SP Page Builder and try to start a new page, the page builder loads, but there's only an image I had loaded into the media in the background. The left sidebar has options for layers, layouts, and media, etc. And, if I click to load a pre-made layout, the pop-up screen appears to give me the choices of layouts. That part seems fine, but when I choose a layout page to import it says (in green) at the bottom right that the layout has been successfully imported, but nothing appears. There's simply the image (media upload) in the background. I can't drag add-on blocks onto the area, nothing.

I'm using Joomla 4, latest Helix Ultimate template 2.0.11, and the latest SP Page Builder 4.0.6.

I've just started building this site on a sub-domain which is only displaying that uploaded image (for some reason).