Display Rollup Total at Row Level - Matrix Visual

Hi, I have a data model as shown below.

I am trying to show a rollup of calls by employee.

The desired result would look like:

(#1) No Reporting Chain Level selected

(#2) Select Senior from Reporting Chain level slicer

See Jessica's calls and the sum of calls for all employees reporting into Jessica.
I'm defining an employee reporting into Jessica as Jessica being present in "ReportingChainLevel2" column in Employees table.

I have tried using a measure like below but it doesn't produce the desired result.

CALCULATE (
    SUM ('Employee Calls'[Num. Calls] ) ,
    ALLEXCEPT(ReportingChainLevels,ReportingChainLevels[ReportingChainLevel])
)

I'm open to all suggestions.

Thank you.