Rally Lookback API: SSO Authentication Errors

Our organization uses single sign-on functionality to log into Rally automatically for each user. Wit custom apps I have created in the past which use the Web Services API, this doesn't appear to cause any troubles, however, when a user who has SSO enabled tries to run an app which uses the Lookback API, a login box appears (shown below). Neither the user's SSO credentials or their previous Rally login credentials seem to work in gaining them access to the API.

My assumption that it is SSO causing this problem is strictly based on the fact that the few of us with it disabled do not run into these problems, however those using SSO encounter it every time.

Has anyone experienced this issue before?

Jake's team at Rally deployed an update that should have resolved this issue. Don't hesitate to post back if it's still occurring or if there's other concerns.