HEllo @Al22,
Welcome to the QucikSight Community, it is great having you here.
Without looking at the data, visual configuration and calculated fields it is hard to come up with an answer, I have not faced issues with applying 2 filters in visualizations. Maybe this is related to LAC on your calculations?
If you could recreate your issue in a demo dashboard in Arena we can take a look at how your setup is workin.
Or paste some screenshots of your filters configurarions and visuals. It is also always useful to create a table visualization that shows the same fields used for the visualization to find out what is the impact of the filters in the calculated fields/aggregations.
Hope this helps!