The system consists of three pairs of jacks: front two, middle and back left, and middle and back right. Each jack in the pair is fed from a tee, so they will each have equal pressure between the two. One jack in the pair will always have more friction than the other so it will extend first until it contacts the ground, then the other heads down.
The second thing to think of, is that the system senses angles. It has no idea how long each jack is extended.
So when you hit auto and it says "grounding jacks", it is pumping fluid (left side first) until it senses movement. Once the jacks are grounded then it works on leveling the unit.
I'd suspect that your left middle jack is still a bit tight, and the back jack touched down hard enough to bump the camper and fool the system that the left side had grounded. And since that was the high side it never called for any more fluid. If you go to manual mode and extend the left side the left middle should finish extending.
2014 Silverback 35QB4
2012 Ram 3500 6.7/slushbox