• Create a new 3D project
• Open multiple property editors
• Select a random node (not a material)
• Lock all of the property editors
• Select default material, right click and press "Edit material"
• All of the property editors are forced to select the default material

Suggested solutions:

• Show the material in a new property editor.
• Show the material in only one of the currently open property editors (priority for the unlocked one if exists).
• Not show the material if there are no unlocked property editors.