Good catch - what you’ve found is somewhere between a bug and the way things are.
When you’re using Roon with the DSJ, the Bridge II stays fully active - basically, the Bridge II holds the connection with Roon in high priority to ensure stable performance. This means once you change the volume in Roon, the Bridge keeps that particular channel of communication open even after you finish adjusting the volume. This allows for easy subsequent volume changes. It’s simply how the Bridge II module handles important streaming communication.
So, our engineering team is aware of it, though it would take a lot of man hours to cook up a clever workaround. We obviously want to maintain the current high priority streaming, so finding a method to work within that framework is tricky.
So long story short, our engineering team has this particular bug on their backburner. If one of the software guys comes up with a clever fix, we’ll implement it. Otherwise, we’ll address it with the Bridge III.
I hope this answer helps!