I've never experienced this when I was in college. In fact I couldn't wait to get away and be in charge of my own life.
My guess would be the kid has not bonded with any new friends, joined any organizations, or attended any school functions or sports activities. Most settle down in their sophomore year.
Another possibility is they have a "girlfriend/boyfriend" they're hoping to hold onto in their hometown. It is extremely difficult to keep a long distance relationship going for teenagers. The reality is most of us move on after a couple of semesters.
Lastly it could be they never really wanted to go away to college to begin with. They may have felt obligated to do so because it was "expected" or they did it to make their parents happy/proud. If you're doing something you don't want to do then it's impossible to enjoy the experience.
As a parent I would not insist on wasting my money on a education my child does not want. However I would ask them; "What do you plan on doing with your life?" (and then I'd shut up and listen)
I would not allow them to move back into my home "rent free" unless they were attending community college full-time, otherwise they'd have to get a job and pay me rent. College may not be for everyone but at some point a person has to develop a marketable skill or trade to live a decent life.
The goal of any parent is to prepare their child for adulthood. After age 18 they are considered adults and have to take responsibility for (their) choices. Some kids will never leave the nest as long as they have all the comforts without having to follow rules or pitch in. Being "uncomfortable" is what motivates us to do better and try to have more in life. Best of luck!