They are balling in the empty upper super because that is how they have been doing it for hundreds of millions of years. Put frames in there and your feeder above a solid board like over an inner cover hole.
Checked yesterday and the ball is getting smaller.I did a cutout and the bees did the same thing for a few days. I agree with the other post. That's what they do.
I gave it a few days and a frame of eggs and they moved back to the combs. No worries. They just gotta settle down.