First off, if it was leaking fluid from the valve it will be wet. Its an oil so it won't evaporate. If your valve body is damp, consider rebuilding it. I am hesitant to suggest rebuilding the valve because I'm the one selling valve rebuild kits, but if it leaks you should replace the o-rings.

Second, I'm not so sure about the assumption that cracking one accumulator line would drain both. Fairly easy to test: just open the lines in the opposite order than you did last time. If the one that didn't drain last time drains this time, and the one that drained last time doesn't drain this time then they are connected. If the one that didn't drain last time, still doesn't drain when you open it first, its a blocked line.

Finally, it has never been clear to me how the system bleeds itself. But you can facilitate the bleeding of air bubbles through the bleeder screw on the valve. With the wheels on the ground (or ramps) have an assistant start the car, flip the valve lever up to pump up the back end, turn off the car, crack the bleeder screw, repeat. This is the last step when I do the full system flush. Caution: the car should drop down to rest entirely on the springs when you open the bleeder, and if your springs are weak it could squish you! But the idea here (besides bleeding the system) is to see that you actuators respond smoothly allowing the rear to raise and lower.

Right now, my money would be on a blocked hose between actuator and accumulator.