creating a dropdown list of current team members

[rshamah]

I am trying to create a dropdown list with the current team members (member_email) who is_active = TRUE for a particular client_ID. The Team Assignments table has 1 row per team member assignment and lists the assignment as active or not. Any client can have 1-10 team members.

In my Referral Update form, I'm trying to create a dropdown with the current active team members so whoever is completing the form can update the team composition as things progress. The Updates table has a column remove_member_email which I cannot figure out how to setup. 

I made a virtual column in the Updates table assignmentsXclient with the expression here, and that populates with the right information in the Update detail view. I can't seem to get those values into the form-

Split(
CONCATENATE(
SELECT(
Team Assignments[member_email],
AND([client_ID]=[_THISROW].[client_ID],[is_active]=TRUE)
)
), ","
)

I also used this expression in the remove_member_email column. It looks like it works when I click "test" but again, nothing right is populating in the dropdown-

SELECT(
Team Assignments[member_email],
AND(
[client_ID] = [_THISROW].[client_ID],
[is_active] = TRUE
)
)

I've tried enumlist with Ref to Team Members (where team members are stored), and enumlist with text, and all sorts of variations based on other dropdowns I created, but nothing is working. What am I missing??

This is the closest I got with the assignmentsXclient