I think I have received a chat message a couple times but 1) it was too small on the screen to read and 2) by the time I noticed it was there, it was gone (it does not stay up long enough) So I have no idea what someone chatted to me.
I do have the same problem! By the time you can check the riders name, the message is gone. And if it was a private message from a rider, who took a turn at a junction into a different direction, I can’t find a way to send a reply, as the rider disappeared from the list.