The block containing the room number is an 'annotative block' that will only show certain contents if the SCALE of the viewport is set right.
In the SS below, you'll see at what scales it is set to appear at. You'll see, too, that when I select the block, it shows several versions of the block at different sizes. Each size only shows in one of those scales. If you set it to 1/4"=1'-0" it'll show one, 1/8"=1'-0" it'll show a different one. It's done so that it will always appear the same SIZE even if the scale changes. If you don't have one of the preset scales set to your viewport, it won't show any of them.