Issue with Garmin 965 sending virtual run speed

I have a Garmin 965, which I am happy with. However, I seem to have come across a rather odd issue.
When using G965 in Virtual Run, I can connect Pace, Cadence and HR directly to Zwift via Bluetooth. All Good.
However, when I look at my watch, AND at the Zwift screen - although HR and Cadence are identical (as they should be as Zwift is taking it from the watch!) - the PACE is not the same. Zwift is recording some 30-40s per km slower than the Pace the Garmin is showing.
Two files from my Training Peaks are attached.
My treadmill was set at 12kph (5min/km), so the Garmin data is accurate based on that. However Zwift only had me running at equivalent of 10.6kph. The accuracy versus the treadmilll is actually irrelevant, because Zwift should just blindly take the pace from the Garmin, just like it does for Cadence and HR. So what is going on? Any ideas?
Garmin 965 Virtual Test - Garmin Data
Garmin 965 Virtual Test - Zwift Data