I’m encountering a lot of this in a current project. I can’t solve it using manual note spacing, and the parts are quite compact of necessity (although there’s sufficient space on the system).
What’s the best way to fix this without completely changing the layout? Am I missing something?
I don’t think there’s a good way of handling this, but you certainly should be able to do it with manual note spacing. Moving this handle right:
results in this, which is pretty ugly but probably the only solution, given a bar rest needs to be centered in the bar:
Thanks. Yes, I did that, but I was hoping to be able to center the bar rest “visually” in the available space… that is, ignore the space taken up by the grace notes and center it in the remainder of the measure. Some more flexibility here would be helpful, I think.
What, I wonder, would be the difference if the grace notes were after the barline? I assume you are recopying for a composer who insists on this.
Unfortunately yes, they need to be before the barline.
If you have the time and you’re really sure you don’t want a centered rest, you could cheat it with a rest-mimicking notehead wih suppressed playback (and hidden stem, if it’s not a whole note). Bit of a pain to set up but would probably duplicate ok once you had the first one in place.
I’m not at my computer at the moment, but I thought about explicit whole and half rests, hide the half-rest, and it should give me a spacing column. Not sure if that would work.
I am at my desk, and yes, that works nicely.
I notice it can even be faked in 4/4 by shifting a half rest up ½ space. 
I opted to do a whole rest + half rest and hide the half rest, then did a little manual spacing:
