I have the same system. 2017 3661RL 6Pt Hydro. The same thing has happened to me before a number of times, and here is how I correct it. I agree entirely with Carl n Susan that the parasitic load is most likely the cause.
1. Place the rig on as level of a surface as possible.
2. Un-hitch (Pull tow vehicle away)
3. Place a four-foot level (The longer the level the more accurate you'll be) just inside the main door and pick somewhat of a center point in that area and check for level front to back and side to side. Make note of any adjustment needed.
4. Go to LU control panel and place the system into zero point calibration. 10 pushes of FRONT button. 10 Pushes of BACK button. The system will beep and the keypad will flash all lights. A message will appear stating "Press ENTER to set, POWER to exit.
5. At this point, if you got lucky and your manual check with your level showed that the unit was in fact level. All you have to do is hit ENTER. If the unit was not level during your manual check. Use the keypad to make the neccessary adjustments to bring the rig into level. Checking your manual level point as you go.
6. Once your satisfied with your manual check of level. Hit ENTER. The LU system will set its memory for the new zero point and power off.
7. Power on the system and retract the rear and mid jacks.
8. Hit the AUTO LEVEL button to test. The system should now successfully return to level automatically.
Hope this helps...I am going through some issues with my LU currently. EXTERNAL SENSOR (Rear level sensor) error. Been troubleshooting for the last few days and LCI is telling me that the entire main controller is bad. One of the things that I learned during this process is that if your LU throws an error at pwr on that will not clear and seemingly leaves you stranded with jacks down. Do the following. Locate, either the main 10 amp fuse for the LU system or the main power harness connector on the controller. (As you look at the controller it will be the right front connector) Remove pwr for a few seconds and reconnect. The unit will clear itself and not power back on allowing you to enter the zero point calibration. Go into calibration mode and use it to manually retract. It seems these units have a few scenarios that they can fail into.
1. Full failure that requires true manual intervention to retract. The "DRILL" method. No electronic assistance.
2. Partial Error that can be cleared and the system still manually operated with electronic assistance.
3. Partial Error that can NOT be cleared. Must pwr cycle and enter calibration mode to operate jacks with electronic assistance.
Again...Hope this helps.