How can I get my live track to activate automatically as since the big crash it will only work manually?

Should be set to "Auto Start" under Menu, LiveTrack. You should see your device and Auto Start.

Can you post a screenshot of that screen?

Do you have the latest Connect for iOS? Currently at version 4.35.1 as of yesterday.

It used to work fine but now doesn’t activate.

I'm at version 4.35.04.01

Looks right. I would try to unpair / pair using these steps. Make sure to reboot both your iPhone and vivoactive 3

If still no joy, some other things to check:

• What type of activity are you using? Make sure GPS is enabled for that activity.
• The phone has to be with you during the activity
• The phone has to have cellular enabled and have a solid connection
• If you're starting your activity from a known Wi-Fi, like your house, LiveTrack might fail if the connection is weak. Although, this might have been fixed in recent updates.

Thanks. Tried most of this stuff, just unpaired and rebooted and will see how we go

Did you get a fix for this? Just noticed mine hasn't auto started since Tuesday when I updated to 4.35.1. 

Using Fenix 5 Plus on Galaxy note 9. Never had an issue before.

Just ran and manually started my live track, using my cellular data and when I got home livetrack had cut out as soon as I left my home wifi.

Definitely something amiss as before the big crash I would turn in auto start with cellular data and away we went no issue.

Out of ideas now, is there a Garmin tech number to call?