Working with "com.unity.inputsystem": "0.2.6-preview", and Unity 2019.1 on windows.
I configured my inputs like so

The aim is to have a cube moving on WASD.
Works fine, the cube move in the expected direction react to key combinasion on the run and stop when keys are released.
But one I release the key I have this exception thrown to the console for each and every frame :
Current phase must be Started or Performed
UnityEngine.Experimental.Input.LowLevel.<>c__DisplayClass6_0:<set_onUpdate>b__0(NativeInputUpdateType, NativeInputEventBuffer*)
UnityEngineInternal.Input.NativeInputSystem:NotifyUpdate(NativeInputUpdateType, IntPtr) (at C:/buildslave/unity/build/Modules/Input/Private/Input.cs:112)