I checked the Layout menu that you have mentioned, and there is possible to switch between languages, but it's not possible to add the numpad. I attached a screenshot of my Keyboard Shortcuts Vizualizer.
If you use another language in your OS, try switching to that language. Also, try enabling and disabling NumLock - see if this helps to refresh its status and AE is able to detect the NumPad Keys.
If these fail, exit AE and doublecheck your keyboard settings for your OS. Re-start AE to see if matters have progressed. If all these fail, then re-start AE and trash AE's Preferences during the re-start.
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