Is, was, there a working fireplace where the problem is? Sometimes heat will cause problems with the old sizing that was used back in the day, which sometimes was made with animal glue( horse,rabbit).
" Glue size was used for such slick walls, since it promoted adhesion, but it wasn’t quite enough in many cases. This is why sticky additives like molasses, sugar, and syrup were common. They helped wallpaper cling to varnished or painted surfaces, but may also be responsible for many a weary old-house owner’s complaint about stripping wallpaper. "
I took this quote from another source. If it will not come off, then you must resort to sanding( with your palm sander) the edges,seams,smooth, skim where needed,sand, clean, prime with Gardz,paint.