Decocking Hatsan semi-autos?

Does anyone know if there's a way to decock Hatsan's semi-autos? I own a Blitz, Galatian Auto and a Sortie. I've tried the standard way of pulling the bolt back, pulling the trigger then slowly releasing the bolt, however, they will still fire afterwards without being charged again, which shouldn't happen if they were actually decocked. I've checked the manuals and tried reaching out to HatasanUSA but they ultimately were no help. Am I doing something wrong here? Or is there another method for these automatics? I own quite a few standard side lever PCP's and this has never been an issue.
 
I have an Invader and it seems like it depends on how much psi I have in The air reservoir. Sometimes it will Decock and sometimes it won’t. I just use the standard method of Pulling the bolt all the way back and then pulling the trigger and letting the bolt forward. It works best when it’s right around the middle of the fill pressure. At least that’s how mine has been working. And lately it has been decocking more. If it don’t I don’t worry about it but always make sure that there’s never a pellet chambered.It’s just that when it’s going to be stored for a long time I would rather it be decocked.
 
sortie is alittle different and fully decocks normally .. the blitz will decock but has a mechanism like a secondary sear, dont fully know how it works .. decocked it wont fire normally and unloads the spring but if the trigger group is disassembled it can allow the bolt to go forward and strike the valve sending it into a full auto dump of the entire air tank lol ... be sure to remove the hammer spring FIRST if your working on it ...