I'm a newbie with a 12FV so my terminology may not be the best here.

When this happens that means the trigger is going into safety mode, this is covered in your manual. If you try to activate the trigger without fully engaging the release in the center of the trigger, the sear will be blocked. This has happened to me when I try to pull the trigger from the very bottom by resting my finger on the trigger guard. Also if your finger is not flat on the trigger it won't hold the release down enough. I did adjust my accutrigger all the way down to light and it doesn't take much to send a round downrange. The 12FV has a varmint accutrigger which is lighter than the standard, but not as light as the target accutrigger...