Reproduction:

1) In any HDRP project create a new Diffusion profile (Rendering->Diffusion profiles).

2) Change the Scattering Tint to green or something, so its easier to understand. 

2) Assign it to a Translucent material

3) Check the HDRP global settings

Result: The diffusion profile is automatically added the HDRP global settings list. The rendering is incorrect, even if there are no errors and the profile is added, the cube is pink(error color).

Expected: Im not entirely sure if the diffusion profile should be added automatically. Maybe there should be a "fix" button instead and profile is only added after user clicks it. Now sometimes is automatic, sometimes we see the fix button. Anyway if this is by design, then im sure at least about the second part - the cube should render correctly, it should be green(in our case) if diffusion profile is added.

Note: This bug best reproduces when you create and assign new diffusion profiles. If you reuse the same one, sometimes you will see the "fix" button which not what the bug is about. 

Adding a project for convenience, but is not necessary.

Possibly regressed here: https://github.cds.internal.unity3d.com/unity/graphics-mirror/commit/ca79d02f10cf6cacfa11be03ed3adb49e3326c0e