Combined Fields filters and missing custom search api fields Drupal 8

I am using Search API and Views to search several fields from several content and media types. For example, I have a custom "description" field for Media->files so users can add a searchable summary field to pdfs they upload to a website. 

While I can get it set up to search all the fields using exposed filters and an "OR" filter grouping, this leads to an exposed filter for each field... which is not ideal. I would rather a single input box that allows several search terms to be passed to each of the filters. 

I have tried to use combined field filter however it is missing a number of the fields passed from the Search API index. For example, below is a simple example searching only pdfs with a custom description field.



Media type and Name are available but not Description or even filename. Is there a way to make these available in the combined filter?

Any other method to achieve the desired result of a single search box for multiple filters would also useful. Just to re-iterate. The filters work, I just want them in a single search field.
It's kind of a beginner error here but in case it's useful to anyone the solution is you want to use the Search API Search filter rather than the combined filter.

It handles the search of the provided index all as a single input field by design.