I was running into the same problem. There’s a similar question on the Blender stackexchange…. It would be nice to have the default viewport color use the diffuse, with an option to override it. Might be worth adding a note to the tutorial. I instinctively just switch to Cycles for almost all new projects. When I make a “real” material, for some reason I rarely run into this, if ever. Maybe my memory is bad.
https://blender.stackexchange.com/questions/75872/not-showing-colors-in-material-mode
Cheers!
