I apologize in advance if I'm repeating what another user in this 42 page thread has already said but I do get the same issue with the auto-hide feature turning itself off. When coming back from sleep I usually get a popup saying something roughly translating to: the auto-hide feature was turned off because there was no taskbar found to apply it on.
In my case, I suspect this issue may have something to do with my DisplayPort monitors natively go into deep sleep mode when the computer goes to sleep. Deep sleep makes the monitors go completely undetected. As such, whenever Windows goes to sleep, I imagine it momentarily cannot find any display device installed and destroys its user interface including those taskbars that are supposed to be getting hidden. I think it may be something along those lines that turns the setting off over and over.
In any case, the fact that an accurate pop-up message is shown to me when the issue occurs means that some error or event was caught that could have been used to reactivate auto-hide in the background instead.