Changing volume in Roon app updates control4 zone volume, but changes in control4 volume do not update in the Roon app. This can lead to a very unpleasant experience if you’ve turned it down in C4, then from the roon app you tap “+” or slide volume up slightly as it will jump to where it left off in the Roon app which could be quite a bit louder than what it was actually playing at.
What zones are impacted by this issue? I just tried a Dragonfly Red zone on my end and the volume is updating properly from the volume slider on both Roon’s end and C4 end. Have you made sure to link your Audio Endpoint and Audio Volume properly as per Page 7 of the User Guide?