Bug Hdrp - Planar Reflection Probe turns black with Forward and Msaa

Hi there,

apparently bugs have a way to find me.

As per title, within Forward Lit Shader Mode and a combination of Default Frame settings (Tuning on Msaa within forward and turning off refractions) breaks the planar reflection probe showing only a black mesh on reflective materials if smoothness is not set to 1. The video shows more clearly the issue described.

To Repro:
*Using Unity 2019.3.15f1 Hdrp 7.3.1 - Repro also in Hdrp 7.4.3

1. Create a new HDRP Project;
2. Set Up the scene with a realtime Planar Reflection Probe;
3. Set Lit Shader Mode to Forward;
4. Set Msaa x4;
5. Go to HDRP Default Frame setting;
6. Turn on "MSAA within Forward";
7. Turn off "Refractions";
8. Reload the project and observe the issue.

It took a while to find the culprit combinations