If the mods password is set. Editing place holder text in any rooms will results in that particular room cannot scroll back to previous history. That button will disappear. It might be resolved spontaneously by time, or changing the mods password, or reverse the placeholder text.
https://files.catbox.moe/svj3cv.mp4
here is a screen cap of the issue happening on one of my gens. i may be wrong but i believe the issue has to do with having more than one person as a admin on the chat. im just guessing that though im not very good with code so im sorry if this unhelpful