In webinterface you can set different time filters for Events in calendar.
One of those time filters is called 'Selected Day'.
If you choose it, it will not display the events of the selected day on the right pane.
It will instead always show the events from 'Today' which is another filter.
It does not matter, which view you use (Day, multi Day, Week or Month).
It does not matter how you select the day, either by using the arrow keys or the mini date chooser behind those.
You never get the events from the selected day.