If I copy material from two staves, select one different staff for Paste Special:Reduce but accidentally hit Paste Special:Explode instead, Dorico immediately quits. Granted, it’s my mistake, but…
Just letting you know.
This isn’t a general problem, Lew, so I suspect there’s something about the specific material you’re trying to Explode that’s causing the crash. If you can reproduce this at will, please attach the project in which you can make it happen, and we’ll take a look at it. Doing Help > Create Diagnostic Report to collect up your crash logs etc. will also be useful: that will create a zip file on your desktop that you can then attach here too.