I am wanting to send people to one main email list. I have a few different ways people get to that list so I am wanting to use Flows to send different emails (initially) to my opt-ins depending on where they came from. And then after a few emails they would end up getting emails from my main list. 

Specifically on one of my forms I created or added a source value for my form to make it more identifiable but when I go in to the Flow Filter to select that source value, I see no option to choose it. Not sure what I am doing wrong.