"Trish".....Glad to see that "007" hit your issue on the head and you were able to confirm it. As a policy, I always operate my slides with the coach plugged in if I can. When I arrive I connect all of my utilities first so I don't have to crawl under a slide to do so. This ensures my slides have full power. I do the same when I leave.
If you're boon docking and have run your batteries down, it's best to have the generator running while bringing in the slides.
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor