When browsing on mobile or in the Discourse Hub app I can’t reply to a chat message in order to create a thread.
Single press on a message brings up no menu (switching to request desktop mode fixes this, but can’t do that within the DH app).
Long press opens the alternative menu that has no reply option listed.
Seems the mobile version needs fixing to support the single tap to open the react/bookmark/reply/more menu. Either that or add react/bookmark/reply to the more menu that is available via long press.
I’ve just given it a check on iPhone/Safari and it seems to be working okay (though I haven’t tried DiscourseHub). On mobile, I long-press to bring up the menu, and the reply is on the right: