I would check the connections to the motors. Low battery can cause that sort of thing too. On your model you should have two hydraulic slides and two electric slides. I'm not sure which is which on your coach model.
You should be able to move all your slides with or without the engine running when on shore power, but it usually works better if you have solid voltage to the slide or hydraulic motors. Some are touchy but usually it's the jacks that need to see proper voltage at the control module and often one needs to have the alternator on line to provide proper voltage especially if the chassis batteries are a bit low...
I can move all of my slides with or without shore power and with or without the engine running. I do have to have the parking brake on AND the key must be in the run position at the ignition switch or there is no power to the relays from the slide switches.
Jay and Joyce.. and IZZY the Havanese guard dog
2009 Tiffin 42 QBH on Spartan, HydraLift, DualSport mosickle, Jeep Cherokee TrailHawk toad, AF1 brake system