Chances are you are on a surface that is too far out of level for the auto level to level without taking the wheel off the ground. You can try to level manually or place cribbing under the wheels on that side.
Ditto what everyone else has said. I got a levelmate pro and installed it. While I don't need it for the leveling process, it helps me figure out if I need to put my tire levelers out on one side. Usually if one side is more than 1.5" out of level, I go ahead and put them under the tires and get it to an inch or so level side-to-side to make sure the tires don't come off the ground. I got the drive-on tire levelers (looks like curved wedges) too. There's a few different brands out there. Here's what I got: https://www.amazon.com/gp/product/B09NJSXRRB/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1