For KOE, you need to type in the desired user name, then KOE should find it. Not sure why the drop mechanism does not work. To share something below the mailbox of a user, the user to which stuff is shared needs folder list permissions on the root of the mailbox plus at least read permissions for the item itself (e.g. a calendar).
I’m having a similar issue here with the newest KOE. Typing the desired username works, drop down works too. However the “OPEN” button is always deactivated. So I can’t open any user, neither through selecting or typing.
Everything else just working fine. Sharing folders and calenders through webapp is working, so why does it not work with KOE.
I must be doing something wrong, just cant figure out what.