Not able to save sets

First I am surprised that Update Library creates some lists automatically, but there are many that are never created. For example the entire Marx Brothers group of films. So I tried to make my own set for them.
I select a movie in my list -> Manage -> Manage Movie Set -> Add movie to new set. But the set never shows up in the Movie Sets list. If I go back to that movie and try again, it indeed acknowledges that it belongs to the new Marx Brothers Collection that I created and offers to remove it or keep it in that set. But when I go to add other Marx Brothers films the newly created set doesnt show up in the list. And the icon in my list for the film that I used to create the set still shows SD instead of the collection icon.

What am I missing here in creating a new set? And shouldnt my Marx Brothers be automatically grouped into a set by my scraper when updating?

I am new to Kodi but have succesfully added a couple hundred movies and TV shows so far using the typical newbie install scraper. I was going to list it here but I cant find it right off in settings. It’s the stuff listed in the Kodi Wiki for new installations. I have not customized any of that. But it seems like my scrapers are dropping the ball on grouping sets.

Thanks!