HWH Jacks Retract After Leveling

I was having the same problem. Called my repair guy and had the him look at the jacks. He raised them manually doing the back ones first and then the front. He raised them to max height and then checked the hydraulic fluid level. The tank was near empty. He explained that when the tank gets low that it will suck in air and that will cause the rear jacks to settle back down. Kept it in the up position for at least an hour, drove to local auto parts store and bought two quarts of transmission fluid. Then I added a half quart of transmission fluid and then raised and lowered the jacks on auto several times. Works fine now (24 hours later they are working). When I bought the motorhome a bad jack was found and it was "repaired" but they may have forgotten to refill the fluid tank. The repair guy said that when the jacks are auto leveled they do the front first which led to the problem of the rear jacks sucking air.