I’ve had this problem a couple of times where I’m getting seams using the cubmap TOP and when using the render TOP in cube map mode (rendering a sphere with no seams). I haven’t had this problem when rendering a sphere on all six sides with six cameras though. The image in the comp below should wrap seamlessly am I doing something wrong?
I’ll need to look into why it has seams since I turn on a new seamless cubemap feature on newer GPU.
The way to fix it for now is to change the extend mode to Hold or Mirror for the U and V coordinates. (Under the >> submenu for that Map in the Phong MAT)