Gutenberg Not Showing Up!!

When Gutenberg came out I disabled it and was using Site Origin Page Builder with the Classic Editor. I can’t seem to figure out how to get my wordpress to use the Gutenberg now! Am I going to have to add an additional plugin? I thought Gutenberg was built in?

Note – I tried clicking the do not use page builder on new posts and this doesn’t change the way my screen looks – still shows the classic editor! I also don’t want to delete the plugin because all of my posts are built with it! Thanks!