I recently updated my Garmin Instinct 2S Solar to software version 9.23. Since then, I have gone on severals runs that have not generated a VO2 max result after my run. All runs have been well over 10 minutes of consistent running at greater than 70% of Maximum Heart rate (which is what the manual says is required for a VO2 Max calculation). My watch was working normally with old software versions, and would generate the VO2 max score after the similar runs.