... over my career I’ve been able to partially solve some very tough engineering problems in my dreams
Same here. I used to think that there was something odd about me being able to do that, but it appears that quite a lot of engineers are the same. I don't know how it works.

Hey Gordon, I too thought I was unique, but apparently this phenomenon is not that rare.
What I can say in my case is that many of the problems I worked on took my team days if not weeks to finally solve so this gave me lots of opportunities to try to exploit the power of dreams. What I learned was I had 2 opportunities each night; prior to sleep entry I would re-state (in my head) what the problem actually was and then at sleep exit and prior to the alarm clock going off I'd try to extend that zone and think about possible problem solutions. In both of these zones I'd try to review and process the latest problem-solving activities we performed. I'm thinking somehow this must be transferrable to music creativity.