A student of mine found an interesting bug this morning - from the schedule summary page, if you click 'study' and get a new terms list, then click the back button on the browser to get back to the schedule page, the 'study' button will no longer work unless you leave the page (go back to dashboard etc) and go back to it. I've replicated this both on my own account and on the app as well. Only happens from the summary page, not if you go directly from the dashboard.