Garmin Training status stopped working

Garmin Training load, as supported on a range of their devices (eg. Fenix 6 in my case), has stopped working a week ago. Last time it worked was 31/8, and any activities from 1/9 onwards for both free rides and structured workouts have failed to affect training load. Earlier this year, the need to dual record activities was negated by Garmin making some changes. I’m unable to link to the article though.

I’m using Zwift via Apple TV and a Kickr Core, so there are already well reported bugs and subsequent attempts by Zwift to fix these with a new game release. Currently I’m not sure if this issue with Garmin’s Training load is related to changes Zwift have made or not. Interested to read the experience of others and whether this is isolated to Apple TV users or not.

I’ve had feedback on another forum that indicates this is more than likely a Zwift issue.
Another user is using a Garmin Edge 530 and an iMac for their Zwift setup. Neither of these use the same firmware/operating system as my devices.
Garmin have advised that no VO2 max related data is being recorded from Zwift, which in turn prevents the calculation being made.
Is this something else that has been changed/affected with recent Zwift updates?