I agree that the dip tube is positioned too high. Why do manufacturers do these things?
First, make sure you use pipe thread tape and tighten everything well on the inside, so the dip tube is sealed inside the port. That will prevent air ingress, which is one reason the siphon can be interrupted.
Second, when you run off into the fermenter, use a tube on the outside that dangles well below the kettle; don't just use the spigot by itself. Otherwise flow will stop at the height of the spigot.
Finally, insert a short bit of silicone tubing (the kind used for floating dip tubes) into the stainless opening, and squish it up there until the other end just barely clears the kettle bottom. You'll get more wort that way.
I'd take a photo if I could, but hope that's self-explanatory.