To find which category a list from onMessage > Content is in when the category title is unknown, an advanced list can be created to show this information.

In onMessage > Content > Lists, list content can be found by searching the list category:
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Note: If the list category is unknown, but the name of the list content is known, an advanced list can be built in Core to find out which category the list is in.
To create an advanced list to find the list category:
  1. Navigate to Lists > Manage Basic and Advanced lists > Add > Create Advanced List
  2. In Select Objects add List and List Category User-added image
  3. In Display Fields > Select Fields
  4. Select from List List.List Id and List.Title and from List Category select List Category.CategoryUser-added image
  5. In Filters select Field: List.Title and Condition: Contains and type in the title or a part of the title of the list
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  1. Select Preview to locate the List Category the List Content is in

An alternate method that can be used to search for the List Category if the URL is known is to find the numeric string that follows the pk=60778 in the URL. This is the List ID and can be added as an object to the list as well.