Say I go to DCIM/Camera and tap on one picture, it opens with the viewer of my choice (in my case I prefer QuickPic but I tried several others) and I can see the picture, but I can't slide to see the next one. Somehow Solid Explorer opens the app in a way that only the selected picture is viewable, like it was the only one available in a directory. Other file managers work well on this, I open a picture, then I can see all the other pictures from the viewer itself.