I’ve seen this 2/2 times with the 7006 beta. I sign in to a Feedbin account, and the account is added, but the pop up doesn’t dismiss. The dialog stays there, with Add Account enabled, but if you try a second time, either nothing happens or you get an alert the account has already been added.
Here’s a screen shot (password is blank as I think iOS hides it) where you see the dialog is still there, but you can also see the folders from my Feedbin account at the left. I’ve cropped it to hide my email address from the from 
