minimized appointments in calendar despite enough space

[dbh]

Hi there!

In my calendar (monthly view) I have the following constellation: there is a week marked continuously as a school-holiday. Additionally there is an 1h appointment on one of these days. In other cases the hour appointment is shown as an abbreviation in the selected color. Now it is only a tiny yellow marker weakly indicating that there is an appointment hidden (see red circle in attachment).
I would like to get the standard view back. What can I do?