Have you tried setting the decay time parameter to the minimum value for your freeze-enabled reverb? This works for me, no need to turn it on and off, and the freeze still works fine.
Really? If so, this would be the best option. Having too many reverbs and delays makes the Kemper hang or behave strange ways.. So you just freeze the reverb, and then dial it in once it's frozen, and it has it's own frozen settings?