Fenix 8 is recording my pace incorrectly

Fenix 8 is recording my pace incorrectly when I run on a treadmill or a Virtual Run activity. Usually at around 4kph no matter how fast I have the treadmill moving.

This means that I am shown as running a greater distance than I actually have.

At the end of the run I re-calibrate to the actual distance run. But I get the same behaviour on the next run.