Error / blank popup when trying to change signed in user

[Jason Savard]

After initializing the buy flow and the popup window opens (sometimes I even initially get this error) or when clicking the sign out at the top right of the popup and signing in as a different user. The error in the javascript console is...

Uncaught Class$S1968: Must provide a target window

[Patrick Casey]

I just got this same error in testing a sandbox version of an app. Closing the blank window and hitting the "Try Again" link in the dialog underneath it opened a new non-blank popup so it kind of worked, but I can imagine a buyer might be turned off and give up.

So I'd like to hear a fix/answer for this as well.