I want to create a view that is limited to specific categories while also allowing the user to filter by those categories but it seems you can't do both? Is there a way around this?
For example I want a view that shows me post type - resources, and only resources tagged with custom taxonomy - whitepapers, reports, videos, e-books (while ignoring all other categories in this taxonomy).
Easy enough to set this up so far.
But now I also want users to be able select with a dropdown from those four categories as they please.
It seems you can't both set a filter query and a selector for the user to filter these?
When you set a query filter it applies permanently, on every page load, where you specify—in this case—the terms that should be applied to the query.
When you add a front-end filter, it is also using a similar query filter, but instead of you manually specifying the terms in the View settings, the terms are passed from the front-end filter via a URL parameter.
You either set the terms manually in the settings, or the front end user sets the terms.
What you can do is use the API, specifically the wpv_filter_taxonomy_query hook, to modify the View arguments.
You would check whether the URL parameter for the front-end filter has some value, and if not (e.g. when first loading the page), set the taxonomy terms that you want to otherwise enforce.
