Immersion has disappeared from Duo
I do not see Immersion at the top, and it is greyed out underneath my Strengthen Skills button saying there is no documents to translate. Did something happen over the weekend?
This often happens when switching between old courses with immersion and new courses without (like Dutch). Assuming that you're in a language that supports immersion, use this url https://www.duolingo.com/translations . It will take you to immersion, and the button should return.
To add to what knittingirl said, if you are taking a course that is in Beta (Phase 2) it might not have Immersion. You can check which phase the course is in by looking here: http://incubator.duolingo.com. Also, if you are signed into a Beta course with no Immersion and don't see Immersion when you switch to a course in Phase 3, try refreshing the page. If that doesn't work, empty your browser cache and come back. Hopefully that will help. ^_^