just before sending to support, as anyone of you ever seen this behaviour :
- My form has a mandatory Attachment field
- So item can not be saved without any attachment
--> After 450 items created in the list, I see about 20 wihtout attachment ! I tested to edit one, put exactly the same file, and it works great !!
Already heard about such a "randomly attachment disappearance" ? Probably somewhere between Nintex item saving and SharePoint....(or between user's chair and keyboard)