No they can be ranked, I'm actually hosting a game jam of my own and it's ranked. It's called the bestest jam ever (it is) and I have seen it in the search bar and jam list so its working. Did you fill out everything?
Viewing post in Horror Jam
I added a cover image, I think that was the problem because it had no cover image so I think I'm good now
https://www.google.com/imgres?q=cat%20thumbs%20up%20meme&imgurl=https%3A%2F%2Fi....