With the mk20 just hitting the ground you need to be sure you have enough altitude for it to set properly.
The CCIP relies on the radar altimeter which points straight down. The altitude that is below you may differ from the one of your target, so the pipper may be off slightly.
In CCRP as soon as you press the trigger it drops the bomb. Make sure you drop it as the line passes the circle in the diamond on top of the hud. I believe that they are making it so that it is delayed until the line gets to the circle in the future.