On the contents tab, when expanding any top-level section, you get the same sub-items

Also, if you expand any items at the second level, you get the same issue (the same data appears no matter which item you expand). And if you try to expand a sub-item, if it is under a lower top-level item, it will expand that same item at the topmost sub level. Hope that makes sense, I need a better way to explain that...

At first glance, it seems like the Arclight demo instance is doing the same thing: https://arclight-demo.projectblacklight.org/

For example, these two screenshots are from the arclight demo site:

Here's the list of things with the two that I expanded circled:

First one expanded:

And second one expanded:

Note that both have the same sub items!?