I’ve been experiencing the same issue with my Blueosund devices for the last couple of weeks. Roon will queue up the music, but, will then wont play it. Although, via USB from an iMac to a Sennheiser headphone amp or iMac system output still plays fine. I believe, but can’t be absolutely certain that the issue started with the last Roon update. I’m also on version 1.7 (build 571).
Roon is running on a Roon Nucleus, trouble end-points are a Bluesound Node 2 & Flex. I’ve found that even if I’m only trying to play back stored music on the Nucleus, I have to sign out of Tidal (which wont load) and back in again and then reboot the Bluesound device that I wish to play on, after which it usually works again. But as you say, it then stops working again by the next day.
Needless to say, it’s driving me nuts.