Hi - Standard Groupings, Matrix Grouping, and Charts are not helpful in Workfront when you have a multi-select field. The reason being is for that object type, you are only getting back one line item, but you want it to appear independently under multiple groupings. Can't do that.
You can either use a prompt to filter out how many requests were for Brazil (and use another grouping for your chart) or you will need to hardcode the filter and make multiple reports.
The fewer multi-select fields you have, the more you can do with reporting. One thing I suggest to my clients is having a primary field that is a drop down and then a secondary field that can be multi-select. That way you can do comparison charts using the Primary field, but then do filtered reports using both to get the complete set of work for a single (in your case) location.