I decided to open this ticket because i think this is either a bug or iclone cant handle Physx properly. I opened a thread in the forum because i wasnt able to find anyone reporting this. https://forum.reallusion.com/542807/PhysX-issues-CPU-or-GPU-

First i thought its another WIN7 issue, but after carefully (DDU) de and installing drivers and Physx newly, nothing has changed. Then i noticed exactly the same behave on WIN 10 which make me think its a bug or something.

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Certain Hairstyles from the Hairstudio and the "Slim Trench Coat" (probably from RL or the markeplace) behave strange when PhysX is activated. The thing is that the hairstyles require Physx to work properly, i am not shure if all of them are affected. Perhaps some of them are corrupt or iclone cant handle them.
Please simply load any base character and apply "Slim Trench Coat" and "Hair Base Top" from the Hairstudio Pack, then let the char walk a few steps. I add a few images to demonstrate the issue. Switching PhysX OFF under Modify-PhysX will disable the strange behave, but the affected items cant be used properly anymore because they require PhysX to look as intened.