Why can the locking arms pop out before the door reaches the bottom, wedging the door in place halfway down the runners?
There is only one thing that can cause this problem: a physical obstruction.
The locking mechanism is activated when the door reaches a complete stop, and the rod is able to move down inside the door. The rod moving inside the door is what pushes the locking arms out into the catches.
So, if something is obstructing the door on its way down, this will activate the locking mechanism.
If the door stopped because of a device or door error, it would remain unlocked, because the door naturally hangs with the rod in the unlocked position. If the door is locked, there must be an obstruction keeping the door from moving any further.
Physical obstructions may include...
the runners becoming too tight for the door to continue moving down at a certain point
debris caught in the runners
debris at the bottom of the door opening
a bird standing in the door
If you have checked and rectified all of these possibilities, and still cannot get the door to work consistently, speak to the Customer Support team.