Update: on the android app I clicked on options and under settings I clicked upgrade. I then upgraded my APs, they restarted, and then I logged back into the app. I clicked on clients and then clicked on the "showing online clients" text and selected blocked and done. Then I had to swipe down to refresh and clicked on the blocked client. The app now gave me a red filled block button and allowed me to unblock the client.
I missed several updates, so my APs needed be updated a few times.