@beastlybeast I also thought that Collections (Smart or other) weren’t supported at all, however I stumbled across something on the weekend where a collection that I had created was on the Infuse home screen. This puzzled me somewhat, but a great outcome, now Infuse in direct mode is working just find, in that I can see a list of unwatched TV Shows & Movies sorted by date (something you can’t do in direct mode).
Apologies if you already knew this, just figured I’d put some further words and screen shots around this, as I’m sure many others are equally conf-Infuse-d as I was (couldn’t resist the pun, I do blame Plex for making collections very difficult to understand and impossible to discover).
<the following is a plex server discussion, nothing to do with Infuse>
Be aware that some oddness exists with Collections and pinning to Home (hence showing up in Infuse home also). From what I can tell, once you have setup a Collection, do not rename it. Things get weird, specifically if you select Home under Manage Selections, the setting will be forgotten.
To avoid, setup your Collections (I have three TV Shows Un-watched sorted by last episode release date, Movies Unwatched and Movies Kids - Unwatched both sorted by release date) and don’t fiddle with them, just delete and re-create if you need to re-name (I think updating filters is fine).
I’m so happy now I’ve found this work around, Infuse is at last usable, ie giving me the ability to see lists of Movies or TV shows by date.
For most of my needs, I now never need to stray away form Home Screen at all 
Homescreen:
Example of the Smart Collection filter I’m using:
Settings/Libraries/Managed Recommendations (you need to hover over library on the right side) where you turn on Home visibility for each Collection you create:
