Hi there - I have a slate VA3 which I purchased around 10 days ago and it is up to date with the latest firmware (2.60).
I have noticed an interesting bug whilst attempting to use the HRM broadcast feature on the VA3. If you select the 'Broadcast' option from the Heart Rate Settings screen this isn't working properly as none of my other ANT+ devices (Edge 520, Zwift setup using an ANT+ USB stick) can find the heart rate when trying to add a sensor.
The workaround is to ensure 'Broadcast in Activity' is selected and then start an activity- and hey presto, the heart rate is now visible to other devices!
I have logged this with Garmin UK today but they have said as yet they have not received any other reports of this. I would appreciate anyone trying it to see of theirs works and letting Garmin know if not! If yours works, and also be interested. Many thanks, Larry