Mailing List Not Updating

Site URL: http://www.snstephenson.com

My mailing list is not updating. I have tried the promotional pop-up and newsletter blocks. Both send the confirmation email, and I see the page confirming me as subscribed. But then, I'm not seeing my address on the mailing list and my automated welcome campaign doesn't send. I have tried with 3 different email addresses, and nothing is going to spam. HELP!

It's not working on my end either on my site - has anyone come up with a solution? Does it take 24 hours to update? 

I have made sure to click and confirm on the email and they're still not added to the list.

Also having this problem on a client site - would appreciate any insight if you two find any help!

I see this post was about a year ago. Did any of you find out how to resolve this? I'm struggling with the same thing.