Never have and never will use an ex cluder in that manner.If they don't want to stay in what I give them then I'll have to check and see what I did wrong.
Lost one swarm like that once, only they had not taken the boxes all the way.
It appeared they got about half in and discovered,(at about the same time I did) the the hive wasn't big enough. 2 deeps was about half enough. Big swarm.doak