The quick answer is; no, it should not have a stop. The original sticks do not stop. There is no reason the new Happ sticks should.
Having said that ... I just got my 2 mechanical rotary sticks a few days ago from Happ as well. And they too were built with switches that have stops in them.
I don't know who has their brain on backwards at Happ, but this is pretty messed up.
I called Happ to complain and ask for replacements. They transferred me to the tech department. That guy asked what I had ordered, so I read him the part number. He then reads OUT LOUD the description of the stick which includes "12 position shorting switch", he then tells me "that's got a potentiometer in it, you can't avoid the stop" and told me I'd have to just return them if I wasn't happy with them. NOTE: A circular shorting switch is NOTHING like a potentiometer. Period.
A quick trip to Digikey or some similar web site will give you plenty of options for 'continously' rotating 12 position switches in all types of sizes and voltages. Happ is just talking out of their ass and using the wrong part.
If I were you, I would call them and demand replacements. Keep asking for a supervisor until you get satisfaction. There is no reason they can't use a continuous switch like they should have and get it right.
Since I'm me, I carefully opened the switches and 'removed' the stop so that they're continuous switches without having to wait for replacements. The switches aren't really designed to be taken apart though (at least, the cheap crap Happ uses are not) so I wouldn't recommend that YOU do this; I'm just impatient and a little crazy (as evident by my rambling).
Anyway. Happ messed up. Make them admit it. Get new parts.
Good luck.