Using classic Outlook for Windows in educational settings
In the outlook web client pick help at top left, then pick help to the left of that again and start a chat. Tell them the arrow indicating a message was replied to disappeared, along with the message in the open email stating "You replied to this ..." also disappeared. I did this and the reply was an appology stating many users have the same problem and it is being worked on. If you will do this and encourage others to do the same thing, perhaps we will get results.