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.
It’s likely the bug happened only in “tabbed” comment? and I’m sure not the only one, because there are multiple feedback under the comment plugin.
Here’s another “blank” gen waiting for cramp the comment until “load more” shows up. I hope this is “clean and blank” enough because I don’t know how to build a tabbed comment from scratch https://perchance.org/tabbed-comment-load-more-debug