I am trying to create a formula that shows a list of Top 20 staff names based on a grouped count. Futhermore, I am trying to dynamically apply a filter to said list.

The data is being taken from the following table NoCstNoAcr, that consists of a list of users, their respective company and branch.

I can successfully show the top 20 usernames based on the file count – but when I try to apply a branch filter (i.e., show the top 20 usernames in a specific branch grouped by file count), the formula returns #CALC! due to nested arrays.

Below is my code:

=LET(
    branchFilter; D33;
    NoCstNoAcrHeaders; NoCstNoAcr[#Headers];
    branchIndex; MATCH("Branch Code"; NoCstNoAcrHeaders; 0);
    operatorIndex; MATCH("Operator Full Name"; NoCstNoAcrHeaders; 0);
    filteredData; IF(ISBLANK(branchFilter);
                     NoCstNoAcr;
                     FILTER(NoCstNoAcr; INDEX(NoCstNoAcr[Branch Code];;)=branchFilter));
    operatorNames; UNIQUE(INDEX(filteredData;;operatorIndex));
    fileCounts; MAP(operatorNames; LAMBDA(name; COUNTIF(INDEX(filteredData;;operatorIndex); name)));
    sortedData; SORTBY(HSTACK(operatorNames; fileCounts); fileCounts; -1);
    TAKE(sortedData; 20)
)

The branch filter is residing in cell D33.

Can someone help me understand why this error occurs and how to fix the formula so it works correctly when a branch filter is applied?