The source for items is a category of articles. The intro text for the particle does still display, just not the accordion items (articles). I think it quit working after upgrade to Gantry 5.5. I can't go back to my last backup because since then they gotten more paid subscribers - I'd lose that connected data.
I'm not seeing any error message. I put the URL in site details.
If this is related to Gantry 5.5 upgrade, how hard it is to install the earlier version again (not with a backup)...