At login load also contacts you recently chat with
Checking this and reloging/restarting did not help.
When I get a message from person with no FB account via Messenger, I can see it as unread, then open it and chat with the person in a standard window. I can even rename the person to see her/his custom name, but cannot find it in my Contact list.
The only way how to open chat window for the actual person is via a group chat where she/he was involved and double click her/his name in a chat participants list (on mouseover, I can see Status: User and not Status: Friend tho, but since I can chat with other ppl on FB without having them in friends and still see them in the Contact list, I don't assume this is the issue).