Took me a while to work out why the sub division modifier wasn't working for me. I'm using Blender 2.83 and for me "Optimal Display" is ticked by default - which means nothing much happens. Does there need to be a revision for this?
I don't believe mine was doing that when I had installed it. Perhaps you loaded a project that had it?
Same here, "optimal Display" was ticked by default in 2.83...
Great tutorial, by the way!!!