Importing HDRP has seriously negatively affected Project (Everything Visually Disappeared)

Hey everyone,

I'm very new to the community, this is my first post. I'll try to provide as much info as possible so hopefully someone with a lot more experience with the HDRP can help me figure out just what I've done to bungle this up...

As a bit of a preface, I'm designing my first game and have started with Unity for one of my University classes. That class just ended and I am going to continue to develop the game I started, but since I'm still early in the process I was considering how I wanted to go about the graphics. I saw some really impressive features from Unreal Engine 5.1 so I wanted to see how Unity's HDRP stacked up.

I watched a few videos and read a few tutorials and it didn't seem all that involved just to get it up and running, especially with the HDRP wizard to help out. So I downloaded and installed the HDRP from the package manager, and immediately found out that I had clearly missed something major as literally everything in my scene disappeared. Note that everything disappeared visually; the game objects themselves are still in the hierarchy window and for all intents and purposes are still in the scene but could not be seen as the entire scene viewport was just grey.

Also note that I did 'Fix all Errors' using the HDRP Wizard, plus I also selected both of the following options: "Converted All Built-in Materials to HDRP" & "Upgrade HDRP Materials to Latest Version". This seemed to work as intended, except for the fact that literally everything went gray/black. Just to clarify, the scene viewport went blanket grey, the game view went completely black, plus all of my prefabs and materials in the project have also gone completely grey.

This is what my project/scene looked like before the HDPR import: (Luckily I had some screenshots from a few days ago)
8671407--1168179--Project Before HDRP Import.png 8671407--1168179--Project Before HDRP Import.png

As you can see this was a test scene so the terrain was not textured yet. However the trees and other elements have very simple materials that I made directly in unity, just some diffuse materials with a bit of metallic or translucency, nothing special, no actual textures no PBR maps or anything like that. You can also see that the prefabs in the project window show the correct colours and actually shows what the prefab is supposed to represent.

Here's what the project looks like now that I've Imported HDRP:

8671407--1168182--Project After HDRP Import.png

As you can see, there's no longer anything to see...Even the prefab thumbnails are blank.

Now after some research I discovered that if I enabled contributors/receivers in the draw scene drop down I get this:
8671407--1168185--Project After HDRP Import with contributors.png

So at least now I can see that the elements are indeed still in the scene, but I can't really work on the project with it being in this state as I have no clue what anything looks like, not to mention that the the game view remains entirely black both in and out of play mode...

Please help, what in the world have I done to my project, and how can I fix it?

Thanks in advance for any assistance!

Can't really tell just from these screenshots however your default HDRP asset in project settings may need to be set, default "fix all" technically should deal with that however.

Regarding your terrain itself though you'll need to create an HDRP terrain material as you'll be using whatever pipeline you came from.

You may also be using a non HDRP main camera.

With grey screens though. Usually there are console errors