Two related questions. First: does this repro for you or is it something local on my iPhone? https://developers.facebook.com/bugs/172749669520391
Second, anyone have workaround for that bug? Now that FB Credits are required for mobile web apps on the platform this is an absolutely critical thing for us to find a workaround for.
Facebook posted a reply in the bug report stating that this is a known issue.
This is a known issue, and we have a workaround for it:
Instead of calling FB.login, please set document.location to redirect directly to the /dialog/oauth endpoint with your own page as the redirect_uri, and that will redirect back to the page the user came from.