(Cycles) HDR Image stretching/tearing issue

I’m hoping someone could help me with this, I’m trying to make a space scene with stars and a few nebula effects in the background for an animation. I figured an HDR image applied as the environment texture would be best for this.

I didn’t find any space themed HDRI’s on google, so I decided to render my own by following this tutorial: https://www.youtube.com/watch?v=s9eDJ9cbyq8

I followed it as accurate as I could while using a panoramic camera (set to equirectangular) instead of a perspective camera. Everything went well from beginning to end until I actually applied the final render as an environment texture (set to equirectangular) and discovered some pretty dramatic stretching/tearing at the top and bottom of the sky. (HDRI: http://i.imgur.com/iEJpdgd.jpg)

the image I rendered was in 4k resolution (3840x2160). but I also have an HDRI with the same resolution that has just the stars and it doesn’t have this issue. (HDRI: http://i.imgur.com/KKxkWB3.png)

I’ll leave an attachment to the blend file where I rendered the stars and nebula in case anyone wants to take a look at it


space_background8.blend (10.7 MB)