Group By settings breaking AOT Query

The problem I am running into is this:

I have multi-select parameter in a dialog that points to an AOT query.

This is the current arrangement of the query's data sources... I am attempting to create an AOT query that populates the parameter with a list of valid Names.

The issue I'm running into is that once I add the ProjTable data source, the names are all duplicated in the parameter list, yet if I attempt any group by, the parameter shows no values in it at all... they are either blank or occasionally show up as unassigned.

This is frustrating because I am able to get this to work in SQL

Select HCMWORKER.Person from HCMWORKER

InnerJoin PROJTABLE on HCMWORKER.RECID = PROJTABLE.WORKERRESPONSIBLE

GroupBy HCMWorker.RECID, HCMWORKER.Person, PROJTABLE.WORKERRESPONSIBLE

Yet I cannot get this to work with the Settings in the AOT. I've seen some solutions that involve building a view but my attempts still circle around to the same issue, either duplicate names in the parameter dropdown, or nothing.