Enumlist base type ref not populating dropdown list, any suggestions?

[ZOCO_Unlimited]

I am unable to get the Enum List to populate with the referenced table's values.  I have tested the column type as reference w/ the employees table and it will populate but will not with EnumList. I even recreated the tables and a new app from scratch and am having the same issues. 

Anyone out there able to help me identify what is off?

Goal: I need to be able to select multiple employees to send a message to

[SkrOYC]

Enum/EnumList basetype Ref need you to manually add the available values.

Use a Valid_if or Suggested Values expression with a list of the key values, generally on the form of TableName[IdColumn]

[ZOCO_Unlimited]

So I tried that as well, and it works for the email notification, but this is what I run into for the texts:

When I try a dereference, this is the error:

[Steve]

Try this instead:

CONCATENATE([Recipients])