This type of calcaution is resourceful as it iterates through individual issues, and for each issue, check on both labels. the bigger the data cube (more issues imported), the more resources (including time) it takes to check all issues and calculate the value.
You may slightly improve the calcaution using the function Sum() instead of the Count(). However, the principle remains the same - it iterates through all issues imported into the data cube. See this Community post for calculation:
An alternative is to import label combinations as a separate dimension and use if for filtering data. Please see this Community post for a solution: