Are you trying to get your source and medium numbers to only display the related goals# completions values for each source? If so, the issue would be that you are trying to slice the measures in Source and medium by another measure - in this case the Goals Completions. We need a Dimension instead to tie these together. We can do the reverse though - by selecting one of the Dimenion values from Source or medium, we can filter the Goals chart to show the related values. That piece is already working correctly in the viz though. It is possible to create a link from the Goals chart to the Source and medium to show the Sources that make up a selected sub group by adding Source and Medium to the marks card. This will divide up the Goals chart bars however and then the selected Source or Medium chart is a filter for the related Dimension but not for the User measure that appears.
I looked at the data and the goals are not exclusive either (some rows of data have values greater than 0 for multiple goals) so going from goals to filter medium or source would not work even if we pivoted the data a bit to try and create a dimension.