We have a Unity 5.01 system and a few users have new messages, but when they login to play them it saids, there name then Hello, you have 4 new messages and then skips to option 2 without playing the press 1 to play new messages option. If you press 1 it saids you have no new messages. If you leave them a new VM it saids you have 5 new messages but the press 1 option is still not there and 1 saids no messages. The messages are in their Inbox as unread.
Most users work fine, and MWI is working fine for these users. When they read the message in their outlook client, and they are all read the MWI goes off.