Hi. macOS 26.5 introduced a bug involving menu item keyboard shortcuts without modifier keys. For example, it affects a menu item with the keyboard shortcut J, but not the keyboard shortcut ⌘J.
This bug is also present in the first beta of macOS 27.
When a menu item is invoked with a keyboard shortcut that has no modifiers and its validateMenuItem(_:) method returns false, the system beeps and refuses to perform the operation. This is expected.
But then even after validateMenuItem(_:) is returning true again, the app will continue refusing to perform that keyboard shortcut until the app is quit and relaunched. It will also do the same with all other keyboard shortcuts that have no modifiers and are attached to menu items.
I filed this with a sample project as FB22762541. I also wrote about it in more detail at: https://virtualsanity.com/202605/bug-involving-keyboard-shortcuts-for-menu-items-that-have-no-modifier-keys-on-macos-265/
I would love to see this issue addressed. Thank you for your work.