I might be dating myself but I've been using Keyshot since it was called Bunkspeed :)
I'm having an issue I have not come across before with just a simple cylinder having lines along the length, I've tried changing a few settings but no solution yet. If someone has some insight I would be more than grateful.
(https://s7.postimg.cc/8cyxfw0mj/cyc.png)
I had a similar issue a little while ago. In my case, the texture scale was way too small and it was creating odd lines on my parts. I believe it was the bump texture that caused it.
That's dating yourself as a younger member. Because it was Actually called Hypershot. Bunkspeed was created when two groups went in different directions.
Also, need some more information. Did you create the object inside of Keyshot, or from your software? Did you try applying a different material? Is there a texture on the material? Some of those things can sneak up on you if you didn't create the material. Check the material graph to see if there is more than one node. That may give you your answer.
Can you upload your scene? So we can look into the details.
Cheers
Marco
Are you by chance using a Color Gradient node with Repeat enabled?