calendar will not display events in month view?

A few days ago my calendar stopped displaying events in the Month view (where I originally entered them). I can see them in the List view, although I cannot edit them. They are also not visible in the Day view.

Moreover at the top of the screen where there would normally be a "+" button to add events and a "calendar" button to view different calendars there is nothing. Only a heading that says "All Calendars" - however I can't find anywhere in settings to view different calendars if I want. Any ideas?