No overview of upcoming events on Calendar

I cannot figure out why none of my events are highlighted in my monthly overview (lower left, upper right), despite the fact that I have about seven events upcoming this month. I have to click on each date to see whether an event is happening, otherwise I would not know it a few days or weeks in advance what is on the horizon.

Is there a setting to automatically highlight dates with events (vs. those without) on the monthly overview calendar (lower left, upper right)??