Thanks, Mark. I’m seeing the same behavior that you’re seeing - I can use the Classic theme out-of-the box, but can’t create a new theme and use the Silk icons.
One thing I did notice - I created a theme based on classic BEFORE I upgraded to 11.1.6. Silk icons worked. Then, I upgraded, “updated out of date themes” and edited the theme - Silk icons went away.
Thanks for checking into this for us.
