I've had this occur as well, but only with powered objects that are connected through pylons and conduits. For my essential objects like water purifiers, I give them their own dedicated generator that is hooked up directly.
But I have returned to my settlements to see lights and spotlights no longer turned on despite still being hooked up. (It seems particularly frequent with spotlights, which will still be rotating, but there won't be a light on.) If I store them, them put them back and hook them up again, it usually fixes the issue temporarily.