Monthly unit calender always shows events for all units

I have a bookable entity with a "BAT Calendar Unit Reference" field and the display settings are configured for "Month view". It is correctly showing the monthly calendar but inside of that calendar we get all events from all units that have the same unit type.

The reason for this is that the query parameter unit_ids remains empty.

I've beeing digging into the code and found the issue in \Drupal\bat_calendar_reference\Plugin\Field\FieldFormatter\BatCalendarReferenceMonthView. Will post a patch shortly.