The "c" shortcut and the right click menu "Unfold from bus" work a little bit different:
-Using the right click menu "unfold from bus" if the bus is not "on grid" the wire-to bus entry does not connect graphically to the bus but goes to the nearest "in grid point" (I don't know if this should considered a bug or a feature. May be a warning on the fact it is not on grid should be appreciated by the user, but I'm not sure on it since it can be personal)
-Trying to do the same using the "c" shortcut gives "no bus selected" even if a bus has been selected using the mouse, so the (wrong) impression to the ones who use the shortcuts is that the bus has something wrong or is not working.
Workaround: place buses on the current grid or try the right-click menu when you receive a "no bus selected".
Not really sure how we should address this -- all of the "immediate actions" (including the hotkey for unfolding bus) run a selection first based on the grid point nearest the cursor, but the right-click menu operates on whatever is actually selected. I'm not sure how much extra work we want to put in to supporting "off grid" editing using immediate action hotkeys, since the right answer is probably to just put all your stuff on the grid :-)
We could make it a bit less confusing by removing the "no bus selected" popup menu when the unfold action is triggered by hotkey. This would make it more consistent with the other actions that do nothing when there is no nearby on-grid item (drag, for example)