Scenario:
I have a private chat with a person.
I close the window to that person but stay on chat.
When the person I was chatting to then writes me a message, this shows "grey/white" on his side (because I left the conversation).
But then a tab opens at my side - and I don't see the message he wrote above. I can continue conversation fine though from this point.
The above has also happend to me without me first having a conversation with the person and closing the window. It happens a tab just pop ups and there is no text in the window. The person did intiate a chat to me, but for some reason I'm not seeing what he is writing (and text is grey/white on his side).