When making beef jerky in a home electric meat dehydrator you do need to flip the beef jerky over at least every 4 hours while the beef jerky is dehydrating.
However I once when I first began making homemade beef jerky just left the beef jerky in the dehydrator without flipping it and it did dry out just fine.
It just took longer to dehydrate both sides of the beef jerky when I didn't flip it over in the dehydrator.
So while you don't have to flip the beef jerky over in the dehydrator it's recommended to do so to speed up the dehydration time of the beef jerky.
If your dehydrator rack has vent holes on both sides then you may not need to flip the jerky over.
But if not then you should flip the jerky over every 4 hours or so to speed up the dehydration time of the beef jerky.