The shortcuts ctrl+alt+up/down/left/right are reserved by Windows to switch the screen display direction and thus make the shortcuts in Dorico for moving notes by an octave impossible. Gonna have to find something else. Why not just Ctrl + up/down, this is standard in many other notation software.
I noticed the behaviour of ctrl+up/down is different than regular up/down in Dorico, but it is not documented in the key commands help file. Can a developer elaborate?