Non-Ray Tracing Shadows are only cast from lights on meshes assigned to the same Lighting Channel. When enabling Ray Tracing Shadows this is not the case. Lights will still cast Ray Tracing Shadows from meshes assigned to different Lighting Channels.
1. Create a new project and enable Ray Tracing
2. Create a blank level and add two meshes (A floor and a smaller cube on top of it)
3. Place a light near the meshes and make sure Cast Ray Tracing Shadows is enabled.
4. Select the smaller mesh and change Channel from 0 to 1
Result - The mesh with the different Lighting Channel does not receive light from the light source, but is still casting the Ray Tracing Shadow on other surrounding objects.
Expected - The mesh assigned to Lighting Channel 1 should not cast the Ray Tracing Shadow from a light assigned to Lighting Channel 0. Surrounding objects assigned to Lighting Channel 0 should also not be affected by its shadow.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-101059 in the post.