Yeah for sure check the temps.

When I thaw my rats I put them in pretty warm water. Takes about 2 hours to thaw and if he doesnt take it the first try, I go back the bathroom get the hairdryer out and heat it up a bit.
Usually that should help make it seem more alive or real.
My BP always wants them warmed up for some reason.

I dont think switching with Corn snakes is that bad.
Maybe more so for a BP (imprint feeders) but I have changed from Live to Thawed a few times with not only my Corn but my BP a few times.

Just don't stick with live too long or they will have a hard time going back.

Mice and smaller rats have done a number on my corn snake so he is now a little afraid of them I think. and his striking speed is much slower and not acurate at all... a lot of times he will miss the one in the tweezers.

anyway, good luck to ya