There was a recent improvement on how Infuse handles the collections group. The first control for collections is under the Setting menu (Gear) on the home screen.
Under setting > General > Collections (ON/OFF)
“On” will show collections in both the “All Movies” and in the “Collections” group in the Movie Library.
Selecting “Off” will show collections only under the “Collections” group in the Movie Library.
When on the home screen and you go to Library > Movies you’ll have the list of sorting options. If you have selected “On” in the general setting then when you open “All Movies” you will see the movies grouped into collections along with all of the other movies. If you selected “Off” then collections will be shown as individual movies along with all other movies instead of a single group.
You can always go to the “Collections” sort to see the collections in your movie library.
The great thing is that if you want to have your collections shown on the home screen you can long press on the “Collections” under “Movies” in the Library and add it as a favorite. Then the movie collections will show on the home screen as its own favorite. This trick will work for any of the sort options in the library for both Movies and TV shows.