could it be that you dropped shortcuts?
i.e. using "space" and mouse drag to navigate on the screen
or duplicate pages in the "pages" window by dragging with options button pressed? those two (for example) do not work anymore?
This can happen when the OS or another app hijacks those keys or when your preferences corrupt. If you've changed nothing on the computer lately (since it stopped working) try a preference reset. In mac OS, the space bar can get hijacked by Spotlight. The option drag is usually a corrupt preferences.
The Indesign preferences
We have the same problem in our company with 16.4.2/3 in InDesign and Photoshop on almost all 30 workstations.
We could solve this by renewing the login in the creative client. We note that every time the shortcuts are missing, the login was not active. Only Adobe knows why an active login in the Creative Cloud affects the shortcuts.
Only the shortcuts that are active when you hold down the key are aeffected by this.