Do shortcuts with Ctrl+Alt work ?

It seems that shortcut containing Ctrl+Alt don’t work. I tried default shortcut provided with scrivener (e.g. Ctrl+Alt+Shift+N or Ctrl+Alt+Shift+P) and customized one (e.g. Ctrl+Alt+M). None work. Others shortcuts with different keys work in Scrivener. Ctrl+Alt+M in MS Word works also (create comments).
I don’t understand why, for instance, Ctrl+Alt+M doesn’t work.

Ctrl+Alt is a problematic shortcut in that it is often interpreted as the AltGr key, used to create special characters in some different keyboard languages and layouts. Microsoft’s design guidelines suggest this combo shouldn’t be used for that reason, which makes it a mystery to me why Word does. However, we need to revamp the Scrivener default shortcuts to address this, so at the moment most of the Ctrl+Alt shortcuts don’t work, and custom ones with those modifiers typically do not work (and it is not recommended). A few should work, including the global Scratch Pad hotkey, but you can also redo the shortcuts on these with the Keyboard tab in Tools > Options… if you’re having trouble in your particular keyboard layout.

Thank for your quick answer. I will therefore avoid this combination of keys.