When I click on the replied to icon in the mobile chat interface when I have a message selected, I expect something to happen, for instance, selecting the message that was replied to or (less desirable) opening the transcript to that message. Instead, nothing happens. I can long press to bring up the context menu and go to the message in the transcript, but that's a lot of work just to see what a reply was to.
I don't think this is a bug.
When selecting a message, it means we want to perform some action on that message (edit/delete if own message, reply if written by others, etc) hence the action icons lit up.
Seeing the target of a reply-to message is not really an action on the message itself, so it's totally expected not to "work" when the message is selected.