I have received twice rejections for the same reason:
Submission includes assets from third-party sites which are not able to be distributed. All assets submitted must be made by you or be public domain assets that may be resold and distributed.
But all my meshes are created on my own in Houdini and imported to UE, and all materials are all made on my own in UE; all the textures are bought from third-party sites.
Could anyone help me? What should I do?