Being new to Kontact, I'm not sure what is a bug, what is a low dev priority, and what is being worked on. But here's something that's just not helpful:

In Exchange, I subscribe to a couple of calendars. One is a colleague's individual calendar, and one is a team's group calendar. Once I have created my EWS account in Kontact, there are two odd results. One is that the calendar grid to the right of the window shows only gridlines and axis labels. There are no entries. To see an entry, I have to double click the calendar name, which launches another window with the calendar.

The other odd result, which is in some ways a bigger problem, is that my work calendar includes all the entries from my colleague's calendar. I do not see a toggle to exclude them.