Training effect data fields in Garmin Connect (Explore 2)

I was pleasantly surprised to see training effect data fields in my first few Explore 2 rides. I didn’t think these features were supported by the device.

But not everything is there - there is an Exercise Load value (is that out of 100?), but the anaerobic and aerobic fields have no data. I’m using the heart rate broadcast from my watch (Vivomove Style - not a watch that supports training effect)

Is there a reason why these fields are empty? Or is it a mistake that they‘re even there? I don’t fully understand what’s required to get these training effect fields generally, perhaps I’m not exercising hard enough?

For reference, the thresholds of this particular ride: