I set a custom key command for Engrave>Note Spacing Change in Engrave mode (which in the Key commands menu is under edit):

On every Dorico restart, the command disappears from the menu and pressing it does not have any effect.
It does remain visible in Preferences>Key commands though (first screenshot). It never disappears from there.
Now, when making a change in Key commands, i.e. adding or removing any other key command, and then applying that, my key command for Note Spacing Change reappears in the menu and can also be used again:
This has been driving me crazy for weeks until I found out that applying any change in the key commands reinstates this one as well. I can’t recall when this first occured. It might have been with the 6.2 update, but I didn’t use Dorico very actively in Q1 so it could also have been with an earlier one. This has definitely not always been a problem, I’ve had this key command since Dorico 5.

