RPR 2.0.15 / Blender 2.80 / Windows 7 (happens on MacOS as well) / i7 6700 + GTX 970.
Getting faceted result when applying Anisotropy with reflection rotation. It is visible even at 45 degrees although subdued, the image below is for 90deg, rendered on GPU. Scene also attached. I haven't included this in the Nodes mega-thread because the node does work as intended but the rendered result is the issue, which leads me to believe it's a core issue, not a node-related one.
This issue does not occur when using CPU to render, and the result is very different - see image below for details.