Keyboard.key.wasPressedThisFrame resets each frame in EditorWindow

Hello, I'm trying to make editor controls that rely on keyboard presses. But inside an EditorWindow

Keyboard.key.wasPressedThisFrame

always returns true if the key is held down, instead of returning false after the first frame. This is using preview 6 in Unity 2020.1.0b5:

Added to the "EditorWindowDemo" sample:

Code (CSharp):

1.         var keyboard = Keyboard.current;
2.         if (keyboard == null)
3.             return;
4.  
5.         EditorGUILayout.LabelField($"A key was pressed this frame: {keyboard.aKey.wasPressedThisFrame}");

The result when I press and hold the A key: