Create-custom-renderer-feature blur sample does not work on Vulkan

Note: ** according to comments from dev, we should edit edit the doc sample to not use frame bufferfetch as the blur effect samples pixel from another location, not current pixel.

 

Steps to reproduce:

1. Open attached project (RG_FBFetch.zip)

2. PlayerSettings > Graphics API > make sure Vulkan is on top of the list

3. Open SampleScene

Actual results: Only vertical blur works.

Expected results: Both vertical and horizontal blur works

Reproducible with versions: 6000.0.6f1.6450.492

Not reproducible with versions: 

Can’t test with versions: 

Tested on (OS):
Windows Vulkan editor
Windows DX11 editor (rendering fine)
Windows DX12 editor (rendering fine)

Notes:

• The blur sample comes from doc https://docs.unity3d.com/Packages/com.unity.render-pipelines.universal@17.0/manual/renderer-features/create-custom-renderer-feature.html