Quoted from Rat:One of the members here sent CGC a very detailed description of the sound sample issues including comparisons to the original ages ago and they did not take it onboard, so it's not because they don't know about it or understand the problem. I think that member has since given up and sold his game?
https://pinside.com/pinball/forum/topic/mmr-music-volume-bug-known-issue
I put that content in a ticket. 8 months ago they acknowledged, and said they would try and get the fix in the next version. I asked for updates a few times over the months in the ticket with no response. Today they closed the ticket without a response. Would someone like to see if they ended up fixing it?