So I build my cells like I've done before but they don't seem to work, it says they've not been enclosed but they have. I don't know what to do, I destroyed and rebuilt them and nothing happens.
Check if a tunnel is somewhere in the cell. Best way is to use the "remove tunnels" tool across the entire cell. Only visible tunnels will be affected and highlighted.
In addition check if a foundation you created at a later time did not 'break' the cell.
Finally, sometimes dismantled doors do look like actual doors, e.g. like opened doors if next to a gap in the wall.
One thing to check is that the "cell" doesn't extend into the doorway.
I've noticed that as soon as clearing the room type in the doorway, my Enclosed failed problem went away.
Edit: And make it fill the whole room.
I was facing same issue on PS4. I had to destroy them. And remove the default plan. And created new structure with cells. It worked.