I’ve got exactly the same issue. I have posted already some time ago [No sound under roon after waking up from sleep mode], but we closed the matter, as it was working again all of a sudden, but unfortunately not for long.
I didn’t bring it up again, because I think it’s something weired with my system, so I’m quite happy, I’m not alone 
. Maybe there is a solution after all. I’m at work right know, but would be happy to provide more information if necessary.
Thanks
Tobi