In the latest (or in a previous one, but not very old) version of TB for ANDROID when you go at Settings->General did you find a sign in button? On top of the page and it says also "sync your tabs, bookmarks, logins, history". I have made the exact same question on the Tor blog. ANDROID 8.1 . I dont believe that my browser is in any way modified, the signatures seem to be OK. When i tap on the "sign in" button the browser crashes.