My 2015 Big Country has a slight hydraulic leak on two of the jacks when stored during the winter , I leave them down when stored , one is the left front, and the other is the left rear ,the middle one on the left does not leak , nor the three on the right side . What's crazy is when I bring them up , and travel everything is okay ,and no more leaks during our travel . Been in Montana for the past month with no leaks when leveled up .They have leaked fluid the past two winters sitting leveled up . I may leave them up this next winter ,and see if the one on the left rear will leak down or leak .
Neither leak enough fluid to worry about ,and so far just have cleaned them up a bit ,and yet to add any hydraulic fluid .
To the OP, how long did your trailer sit for them to leak down ? Is it a big concern say when traveling ? So far what I have going on is of no concern . I have had to recalibrate the level up a couple times to get it to work .