Top bar menu dropdowns stop working after update

As far as I can tell, this began on an update to 5.8.1. Nothing is working to fix it.
We had a small top menu with locations and one drop-down, while the main menu was under the header.
There seems to be no error message and nothing in the Console log.

That said the links DO appear in the inspector. But they don’t work. The top level menu item is #Locations and then under a short list of locations.

How do we fix this? We just used the standard nav block for the menu. The main menu on the other hand has no issue with the dropdowns.