I was participating in a group workout that was to finish after the group ride that I signed up for started. While in the group workout I was prompted to go to the group ride, which I did.
After the group ride finished I went to Strava and saw my two different activities, which is correct, and the data for both was accurate, but both activities had the group workout as their title.
Did you save your activity after the group workout and before you joined the subsequent group ride?
To my knowledge, that’s still considered to be a best practice, and the only surefire way to avoid multiple rides done in succession from sharing the same activity name is to save the ride, force quit Zwift, then start a new app session for the next event or activity.
Hope that helps!