Error in adding product in opencart 3

I have a very strange error when i add a product. After i have added a product and add another product, it multiplies itself in 2 the same products, sometimes it adds itself up to 4 times. When i use the copy function of a product all works fine. Someone an idea what could be wrong here? I already updatet to the latest version. I’m completely stuck here..

Old issue, your solution is here: viewtopic.php?f=202&t=212501&p=769340