The young ones are not using the poles anymore. Could it be the older ones have kicked them off? They don’t mingle in the run either. Each group sticks to themselves. Hoping to get them situated so they play nice together. Anyone else experience this behavior
Too much experience. Until they mature enough to force their way into the pecking order, my immature pullets generally do not sleep on the main roosts with the adults. If they try, the adults are extremely likely to peck them or worse. So they seek a safer place to sleep. My pullets typically mature enough to move to the main roosts when they start to lay. Usually within a couple of weeks.
The same for the cockerels except I don't have anything to suggest when they mature enough to move to the main roosts. I've seen some move to the roosts fairly young, others wait a long time.
Once they all mature enough they will join more into one group. They may stay apart in their groups some but they can and do mingle without getting beat up. What you describe sounds perfectly normal. At that age my definition of a successful integration is that no one gets hurt. Sounds like you've managed that.

The other stuff will come with time.
They still tend to like to sleep in high places. Often the nests are the logic place (to them) to safely spend the night. The way I solved this issue was to put in a "juvenile" roost. It's lower than the main roosts but higher than the nests. It's also a few feet horizontally separated from the main roosts. Now I almost never get one trying to sleep in the nests. Hopefully you have room in your coop to do something like this. This is my juvenile roost. Definitely higher than the nests and separated from the higher main roosts.
Since yours are now sleeping in the nests you may need to break them from that habit. I know of two options. One is to move them from the nests to the juvenile roosts after dark. Sometimes they get the message really quickly but sometimes it takes a while. This is the way I manage it.
Since you have older hens they are probably laying. You don't want to train them to not lay in the nests. A good way to handle this is to block off the nests after they have all finished laying for the day to force the juveniles to find another place to sleep. Then after it is dark open the nests back up so the nests are available first thing next morning if you don't get down there immediately.
I see you posted while I was typing. Good luck!