Can you sort by favorites?

It's separate from the other sorting options there's a heart on the left side of the ally box where you can choose to put a certain heart colour at the top.

They changed the way this works. They got rid of the "Favorites" button in the sort options and they put a heart toggle on the top left corner of your barracks. Click on that and you can filter all the heroes with a particular heart color to the top of your barracks. Your sort rules will still stay in effect, so if you wanted to find all your 5* flyers with blue hearts, for example, you could set that up.

I sort favorites by color. Example: I love the color blue so all my fave units that I use and don’t use are faved with blue hearts. All units I use but don’t particularly like I keep the purplish pinkish heart. Fodderable i keep as regular heart. Send home units no heart. Perfect IVs must build sooner or later units I keep it as green hearts