Maybe there’s just too much food? If he isn’t eating, then he isn’t hungry, but perhaps wants to make sure he will be able to find it later when he is? I’m all about feeding on a schedule, that way your dog will actually eat when you put food down, and also not eat too much.
I wouldn’t switch to wet food – you don’t want to create a picky eater. I don’t know what kind of food you’re feeding, but changing to better quality might help. If you’re already feeding good quality, then switch up the protein. I changed my dog to a whitefish formula and he went from having bouts of not eating, to licking and rolling in his food >.< He reaallyyy likes it.