Numpad 7 and Numpad 1 were not working for some players. The cause was leftover keybindings from the northwest and southwest movement directions, which were removed a few updates ago — the directions were gone, but the old key mappings were still in saved settings and were overriding the new up/down bindings.
Old keybindings are now cleared automatically on load. If you previously had to reset your settings to make the keys work, that is no longer necessary.
Two dead entries have also been removed from the keybinding list in Settings.
Thanks to 白起 for reporting this, and for the detail that made the cause findable.