When a context menu is open and some action is taken which changes the available options, the menu must be closed and reopened to see the changes. This technique can refresh the window contents automatically: https://github.com/Majiir/Kethane/blob/master/Plugin/KethaneExtractor.cs#L138-L141

I am going on vacation this coming week, If I have time while away I will make an attempt to help with this!