Bug VFX GRAPH files are not saved after closing Unity

Hello, there seems to be a problem with VFX Graph not saving anything that I work on. It works perfectly until i close the program. I am on URP and working in a Collab project with another person.
My procedure is: i create a vfx graph file, drag into the scene or the hierarchy, i click on it, open vfx graph i make desired changes, create some nodes, etc, i click compile and then close vfx graph and Unity. Then , when i come back, the vfx graph is there, but its completely reset, with the basic system.

 

Workaround: Grpah is saved if you click the "compile" button and close the graph window manually (or switch Unity Layout)

 

omg Unity. I lost hours and hours of work because it didn´t save at all. Today I´m running tests, and it just do not save. I did try to copy and paste the project, the VFX graph, restart the computer, make a small change and see if it save, nothing works. Hit compile and close, saving the project, the scene. Nothing makes this little devil to save my changes...
it´s a nightmare :/

 

Is anyone here able to resolve this? I can't save new .vfx files regardless of what I do. I've tested by creating a new project (2019.4.16) and adding just the Visual Effects package. I get the following exception on a Mac

NullReferenceException: Object reference not set to an instance of an object
UnityEditor.ContainerWindow.NotDockedWindowID () (at /Users/bokken/buildslave/unity/build/Editor/Mono/ContainerWindow.cs:224)
UnityEditor.ContainerWindow.Load (System.Boolean loadPosition) (at /Users/bokken/buildslave/unity/build/Editor/Mono/ContainerWindow.cs:259)
UnityEditor.ContainerWindow.Show (UnityEditor.ShowMode showMode, System.Boolean loadPosition, System.Boolean displayImmediately, System.Boolean setFocus) (at /Users/bokken/buildslave/unity/build/Editor/Mono/ContainerWindow.cs:117)
UnityEditor.EditorWindow.ShowWithMode (UnityEditor.ShowMode mode) (at /Users/bokken/buildslave/unity/build/Editor/Mono/EditorWindow.cs:534)
UnityEditor.EditorWindow.ShowModal () (at /Users/bokken/buildslave/unity/build/Editor/Mono/EditorWindow.cs:631)
UnityEditor.AssetSaveDialog.ShowWindow (System.String[] inAssets, System.String[]& assetsThatShouldBeSaved) (at /Users/bokken/buildslave/unity/build/Editor/Mono/GUI/AssetSaveDialog.cs:81)
UnityEditor.AssetModificationProcessorInternal.OnWillSaveAssets (System.String[] assets, System.String[]& assetsThatShouldBeSaved, System.String[]& assetsThatShouldBeReverted, System.Boolean explicitlySaveAsset) (at /Users/bokken/buildslave/unity/build/Editor/Mono/AssetModificationProcessor.cs:144)
UnityEditor.EditorApplication:Internal_CallGlobalEventHandler() (at /Users/bokken/buildslave/unity/build/Editor/Mono/EditorApplication.cs:442)