In the month view, the Kendo-UI Calendar widget displays the days of the next or previous month to fill the remaining space in a week. When a date is selected, it is highlighted.
Imagine the following scenario:
This can easily be repoduced with the demo calendar.
When I navigate through the drop down on the left side to select a field to filter on, it will only grab the first 2 and the last option. When the element is opened it will properly go through all options. Reproducer: https://dojo.telerik.com/AruwArIP
I have made a recording of the bug here: https://imgur.com/a/kIgDa06