The help states "Conversely, when a list is the target of an action such as a map extent change, the list can filter so the data it displays corresponds with the map's new extent."
But in the Map actions page of the map under When the map extent changes - no List element will even show up as a possible target.
Note if I select items in the map the List will change based on it but changing the extent does nothing.
Also is there any way to get the number of items in a list? I want to pass it to an indicator but I see no way. I can pass what is Selected but not a count of the entire list. So say I have 600 features and I use a category selector to bring it down to 10. How can I pass that number 10? If I select all 10 I can get it but no. It would also be really nice to filter the map based on all the features in the list not just the selected. Even a select all button in the list would be nice.
That's strange. Filtering the list by the map extent should work. It sounds like you're doing it right, so I can't say much there.
As for the other questions:
You should be able to set the indicator as a filter target in the category selector element. Also, in the category selector there's a "none" option which allows you to select all features.