My crew don't feed as well in a rack I rotate them once in a while (18-24 months) and the odd thing is they all eat more meals in the enclosure than the rack. (I have a five tier AP rack and 6 enclosures) About 7-12% more meals a year. The temps in my case are all about the same give or take. I have no explanation for this at all.

How exactly are your temps in the rack, both surface hot and cool as well as ambient air temps? Is there a big difference? Air temps in a rack are far harder to control than a enclosure so there is often a big change there.