Opening any world with ray tracing activated and using a custom PBR resource pack will result in block shading and block reflections breaking.

Perfect mirror blocks no longer reflect anything + block shading is broken:

Water reflections are still functional but any reflective block has broken reflections. In this example ice blocks have reflections that cut off in random places and seem to be affected by refraction in some form.

Block shading is completely functional without ray traced lighting.
Ray Tracing On:

Ray Tracing Off:

There is no sign of this happening in any official marketplace maps.

Steps to recreate:
1. Download a community-sourced PBR resource pack (This one for example)
2. Apply it to a world and observe results.