I’m also experiencing a new issue that I believe is related to the force_login=true oauth troubles.
Scenario: I’m logged into Twitter.com in one tab, then I try and authenticate with my app in another tab.
Problem: After the authorize screen pops up, it automatically logs me out of Twitter.com in the other tab. This wasn’t happening previously. This is before I even enter my password in the Twitter authorize screen.
Its happening in chrome, firefox, and IE.