Forerunner 965 - elevation errors

Hi all, my Forerunner 965 has recently started to record wildly incorrect elevation data on runs - see example in attached image on 7k run today and correct elevation data after fixing in Strava. 

I have calibrated the altimeter several times, including just before runs, but the issue continues.

I've seen in posts that others have had a similar issue, but not sure if it is a component failure, or recent software failure?

Anyone else having the same issue - and any tips to resolve?

Thank you in advance.