At the moment, I’m unsure what the Post Loop widget looks like it does in your installation. I’m chatting with the team and will update you as soon as I have more info/guesses as to what the issue might be. That looks like an older version of the widget’s interface. In the meantime, if you wanted to try a few things, you could:
1. Confirm that the Post Loop widget looks the same with all non-SiteOrigin plugins deactivated and a default theme like Twenty Nineteen running.
2. You could send us an export of a page using the Post Loop widget. From within Page Builder that’s done via Layouts > Import/Export > Download Layout. Then, upload the JSON file to a service like WeTranfer.com and send us the link.
Thanks ??