Message menu still have "number"as if it has not been read yet

Could you please let me know what the trigger is to reset the Chat notification counter? I received a chat message this morning, but even after responding to it the notification counter is still showing 1 in red. The chat itself also shows unread above the message. See screenshot below.

I already closed all Waze windows, but that did not help. It’s nothing major and doesn’t hinder WME’s working, but it’s bugging me.