I don't have a premium subscription, I have just downloaded the std version to test it out so I can decide if it's worth buying the premium, at the moment I'm thinking not.
I've tested adding additional modules to the test SP Pagebuilder page from pagebuilder, they work. I have loaded other std joomla modules to the page and they work but your SP addons just don't work. I'ev even added titles to your pagebuilder addon's for the test page and that doesn't show up, it's like they don't exist.