Hi stwert,

Thank you for your reply. The strap stays correctly and looks attached to the guitar all the time.
I tried a lot, but it seems that the guitar doesnt care what I do for settings for ncloth for the strap. It always falls down. Even when I put the dynamic properties for the strap to the maximum for all values (In this case, the strap looks no longer attached because it is stiff but the dynamic constraints are bending..