using Valve.VR isn't importing namespace

This is happening to me with the proper IDE set using Unity 2019.3 with Open VR Desktop 2.0.5 and Steam VR2.2.0. I have regenerated project files for the .csproj from all sources. I have deleted .csproj and .sln as well as .vs files and allowed Unity to regenerate them. Saved closed rebooted etc but the Valve namespace and all sub namespaces fail giving me a repeating error:

" NullReferenceException: Object reference not set to an instance of an object
Valve.VR.InteractionSystem.Sample.LockToPoint.FixedUpdate () (at Assets/SteamVR/InteractionSystem/Samples/BuggyBuddy/LockToPoint.cs:54) "

The LockToPoint script is being called in another script which gives an error “The type or namespace ‘LockToPoint’ could not be found…” while the using Valve.VR.InteractionSystem.Sample; says “Using Directive is Unnecessary”. Removing .Sample from the using removes the last error but the namespace remains grayed out and the reference to LockToPoint still throws errors?

Things like

// (SteamVR) Player reference
public Valve.VR.InteractionSystem.Player player;
public Valve.VR.InteractionSystem.Hand leftHand;
public Valve.VR.InteractionSystem.Hand rightHand;

Which have worked for months all fail now do to a missing assembly reference with using Valve.VR; present.

The only other thing I can think of is resetting the dll reference in Visual Studio Community 2017 but I don’t know how to do that?

Any idea whats going on or how to fix it?

Update. Looked up resting the dll’s and it didn’t help.

Found the issue. Its a Unity bug in 2019.3.12
documented here