Changing the name AND shortcut to an action menu item at runtime does not change the shortcut at all. This seems to happen only when using native menu bar. I also noticed that when changing only the shortcut, it does seem to update on menu item.

Please find the attached example application to demonstrate this issue.

Steps to reproduce:
Launch the app
Open "Edit" menu and select Copy
Open "Edit" menu again and observe, Copy menu item renamed to CopyCopy and there is no shortcut visible