I am not positive I understand your situation, but here goes.
I assume you are still running in high (or low) governor mode on your CC ESC---not the rpm mode. So when you adjust the Ztron to give a ~2ms output pulse (aka "Full Throttle"), the ESC will go to the maximum rpm it supports in that governor mode. As far as I know, this may not actually be "full" throttle from the motor or ESC point of view since the low and high modes had ranges it would support and those ranges may not include full throttle.
But I do assume you did get a higher rpm. As far as the current dropping, this would only be consistent (I think) with the battery voltage also dropping, and also the rpm dropping from the value you started with. You don't say the rpm dropped, but I have to believe it did!