I had a problem, when using auto level, where the coach tried to level and couldn't. I got the error you described, my front jacks were extended and my rear jacks were half way extended. I tried several times with the same results. I never got an indication that there was too much of a slope to level on. After overheating the hydraulic pump and having to reset the breaker (after allowing it to cool) I had my wife try it while I observed what was happening. After the coach used the rear jacks to stabilize the coach, it raised the front to the max extension of the jacks and then tried letting the back by pulling up the rear jacks. When it couldn't, because the wheels were on the ground, it stopped and gave the error.
I manually raised the front wheels off the ground. Added wood blocks under the wheels because you never want to level with your wheels off the ground. Lowered the coach and added wood blocks under the front stabilizers. Re-ran the automatic leveler and leveling was successful with all wheels on the ground and no error.
I hope this helps.
Greg, Barbara and Cody the wonder-pup.
2014 FR3 30DS
(and 2 200cc Scooters)