After you change the pitch of a note that's tied, both tied notes end up selected.
1) Write any chord in which some or all of the notes are tied to notes on a different beat.
2) Scroll among the notes of this chord with your custom keyboard shortcut. It works fine.
3) Once you reach any note that's tied, change its pitch either up or down.
4) The other tied note moves along with the one you moved manually, but afterwards both notes end up selected, which means you can't keep scrolling with that keyboard shortcut.
This goes against the main purpose of that command.