Issue resolved myself.
I have three reports created in BIP (each with Parameters):
1) Control Report - Internal Users -> Works without Issue
2) Control Report - External Users -> Parameter was not working
3) Open SOX Issues Report -> Works without Issue
1) Deleted report 2 and all related items
2) Clear cache and reloaded metadata, etc...
3) Cleared browser cache as well
4) Recreated datamodel
--- Added List of Values
--- Added Parameter and tested -> OK
--- Added Data set -> OK
--- Tested --> OK
Not really sure why I was having the issue I was having.... But it appears to be OK now.