Group workout grouping

Hi

When I do a group workout as soon as it starts I end up 30 seconds ahead then over the ride that could end up being 5-7 mins.
Si basically do the ride on my own, everything else works fine, the cadence and power operate the same as others but on screen I am riding alone
Any ideas

Seems pretty odd. What is the full rundown of your Zwift setup? And does this happen for all of your group workouts, or just some?

Just for group workouts, if I do a group ride that’s not structured then that’s fine
I run Zwift off my iMac to smart trainer by ant plus dongle