Problem: a custom media folder will store the custom list view settings but not show them as being saved if you navigate back to the list view tab. Also, any custom columns show an error when you try to sort with them (default columns like Name sort fine). And in the custom list view the default sort dropdown never shows your custom columns as options.

Steps to create: create a custom media folder (in Settings > Media Types) and define a custom list view, save it, and save the folder item