HDRP wizard doesn't create a default prefab on fix

in 19.3 no problem

 

had to revert to 19.3

 

It's expected that HDRP 7 will eventually break if you use it with 2020.1, it's not meant for 2020.1 at all, but for 2019.3.

With 2020.1, you should use HDRP 8 but it's not been released yet so the best one can do atm is to find a version from github SRP that works with most recent 2020.1 alpha. Often github's bleeding edge is tad ahead the editors we get on alphas/betas so you may need to figure that on out if you go this path. In general, you should just wait for Unity to give proper release if you want it to work out of the box.

I want to mention that this is super typical scenario when using alphas and SRPs, Unity doesn't usually do new releases for the SRPs (for the editor versions that are still at the alpha stage).

For people who like the bleeding edge, this has never been an issue as you can get this combo running with manual work, but if you don't like constantly fiddling with git, I'd really just recommend to wait for the version to mature enough for Unity actually release compatible SRP versions.