HDRenderPipeline - Build hung at Compiling Shader Variants for hours.

Compiling a test build, I can't get it to get past Compiling Shader Variants. I left it for several hours with no progress (but 90%+ CPU usage). Had to manually abort the program. Next attempt produced the same result (stopped after one hour).

Started from a backup again (only difference is no HD Render Pipeline / upgraded shaders), then build took about 10 minutes.

Curious as to what is going wrong... Are times like these expected for the HD Pipeline?

 

The Shader Variants take a long time to compile
Have a look at this thread it covers the same issue here - https://forum.unity.com/threads/whats-wrong-with-the-shader-compilier.519469/#post-3435688