In Photoshop 23.0.2 under macOS Big Sur, when the artboard is not visible (i.e., when the window borders are flush against the edges of the artwork) and the entire image is visible on screen (i.e., no scroll bars), and you Select All, the marching ants are not visible like they should be. Sometimes, depending on the window dimensions, a sliver of the marching ants is visible on one or two edges, but most of the time, they are completely hidden. Here is a video of the problem: