PostProcessing and 2019.1 alpha 13

Unity Post Processing package fails with the following error in 2019.1.0a13:

Shader error in 'Hidden/PostProcessing/Uber': failed to open source file: '../StdLib.hlsl' at line 21 (on d3d11)

I'm running with latest package "2.1.2" that Unity auto-updated.

 

Deleting the Library folder and reimporting everything fixed the issue...

 

2019.1.0b1 Project copied from 2018.3 (reason: I want to add Alembic files, unable to add Alembic package in 2018.3 due to missing assembly, error may be with Unity recorder). Have imported Alembic package successfully and now have curtain blowing in wind - looks nice

However; I then went to add post processing stack back in, which worked, but - all the objects in my project became invisible (meaning; it looks like the mesh renderer has been deactivated on all of them, except it hasn't). To compound the weirdness the game viewport is black, but the camera preview in the scene viewport shows the scene correctly despite the fact all I can see in the scene itself are collision object bounding boxes.

This is an animation project (meaning: I haven't written any code for it, dodgy or otherwise) and all of the packages used (alembic, recorder, post processing) are Unity in-house. I would be quite tense by this point as this is a production job for a client, but for the fact I have of course made shed-loads of backups

Are there any quick fixes for entire projects disappearing that spring to mind?

 

Actually my workaround for the PostProcess errors is selecting the PostProcess package and reimport it.
The error happens randomly at random people and re-appears from time to time. (even in the latest beta)

The Alembic importer is a harder one:

It seems the importer is designed so it DOESN'T work in team projects (at least if you use a common cache server)
This is because it hardcodes the full-path (!) of the Alembic file into the imported prefab and than tries to load the file during runtime from there. So be careful of that.

Also sometimes importing doesn't work (you get a blank file) than you have to select the Alembic package and reimport it, then reimport all Alembic files, then reimport all prefabs/prefab-variants depending on them. (Looks like reimporting an asset doesn't trigger the reimport of dependent prefabs in Unity).

If you want to use Alembic in a build it will work - as long as you run the build on the computer where it was built, it won't work anywhere else - again because of the hardcoded full-path of the Alembic files.
This you can fix by moving the package content into Assets folder and not using the package at all, then changing the importer source code to load the Alembic files somewhere from StreamingAssets at runtime.
But than you need two copies of the Alembic files at two places in your Assets folder and you have to keep them in sync manually.