The Cog Menu > Reset To Default feature resets the property in the Inspector but has no effect on the node itself. Some examples:

D&D a Button
Set Visible property to false
Choose Visible property > Cog Menu > Reset to Default - bug - the Visible Checkbox is re-enabled in the Inspector but the node is still invisible in the Content Panel

D&D a Button
Set Text property to “Hello”
Choose Text property > Cog Menu > Reset to Default - bug - the Text property is set to “” (is this right, should it be back to “Button”) but the Button still shows “Hello” in the Content Panel

D&D a GridPane
Set Grid Lines Visible property to true
Choose Grid Lines Visible property > Cog Menu > Reset to Default - bug - the Grid Lines Visible Checkbox is disabled in the Inspector but the Grid Lines are still visible in the Content Panel