Count Unique w/ Indirect Group Criteria

I want to do a modified version of what is detailed in this ExcelJet post:

https://exceljet.net/formula/count-u...-with-criteria

You can see my modification of this example in my attached spreadsheet. Basically, rather than filter by a specific project name as in the ExcelJet post, I want to filter by a specific project group. A project group can contain multiple different projects. When counting the unique name values for Group1, for example, it should include both Alpha AND Omega projects in the consideration. Here are the expected return values:

Group 1: 4 (Jim, Sandra, Carl, Sue)
Group 2: 4 (Jim, Carl, Sue, Ayako)

I am trying to achieve this with an INDEX/MATCH function that returns a specific named range to an INDIRECT function, but I get the N/A# error when I attempt this. Any help would be appreciated!