FR 945 APAC VO2 max not calculating after an update to SW 5.60. When will the 6.20 row released to apac?

My vo2max is recorded for firmware 5.60.

Maybe you are right about the wrist based HR. I am using a chest strap though.

All of the graphs you have shown are of very erratic HR, appears to be a lot of short intervals if the HR readings are accurate.   Nothing sustained high HR (10-20minutes). Would be good to overlay the pace graph to them in the future maybe (or cadence).    The first one appears to be HR sensor error, super high at start of run...then gradual decline.  The 2nd to last graph is close, almost 10minutes steady HR sections, but they all have a good dip in them, short of the 10minute minimum goal from Garmin (and really want 15-20min).  

Have you read the guidelines or info for getting a vo2max reading for the watch?   

https://www8.garmin.com/manuals/webhelp/forerunner945/EN-US/GUID-3E971364-A756-4057-B22D-C41250B2A82B.html

https://www8.garmin.com/manuals/webhelp/forerunner945/EN-US/GUID-015C6746-435D-48E0-8ED8-CA2C81684E38.html

The general consensus however for getting a good vo2max reading is run at a moderate to hard effort for at least 10minutes steady (ideally 15-20minutes).  Ideally on a flat elevation, minimal wind, good flat surface/paved.  Have at least a 5-10minute warmup, don't pause/start/stop.  Wear a chest strap if you have it.  HR should get above 85% of max.  HR Max setting should your actual max from a field test or end of good race sprint (not by generic calculation!).
Warmup, then pickup pace to 10k or Half marathon pace... hold that for 15-20minutes (should feel pretty hard by 10minutes into it)...then short cooldown and stop/save watch.  I have found a long (15+min) cooldown seems to mess with readings possibly if the workout was very hard (possibly detects the slow jog...with a high HR...and says, "oh, maybe he is slow..." , but it shouldn't so who knows).

Do I need to keep a constant pace for it to calculate? I did set my HR manually by looking back at my previous runs.In the manual, it says to run for over 10 minute with HR >70% with GPS. I did slow down to a jog for a bit but I kept my HR to be > 80% at all times and didn't even dip below 70%. Most of them are more than 15 minutes. The first 3 graphs are when I had a knee injury, so I do think it wouldn't calculate from those. And on the 4th graph, while not with a constant pace, vo2 max is still being recorded.

Somewhat constant pace helps, yes, it is trying to correlate you effort (HR) with a pace.  Steady pace and flat conditions helps this, it wants to see a high HR that is steady or slightly rising ...with a certain pace.  That is then looked up in their data tables to show your fitness level / VO2max.  If the pace keeps changing within a 10min block, this is no longer a steady paced 10min.  Obviously there is some room for movement, pacing isn't always the easiest outside!  I find setting autolap to half miles instead of miles during workouts like that help.  Then 'lap pace' is a bit closer to actual instant pace (but not as jumpy as live/current pace).   OR just watch HR, want it to be just slightly increasing in value, if it starts to dip , just slightly try to hold effort up better.

Thank you. This is very informative. I will try it in my next run. I Will try to keep a constant pace, and not pushing too hard which pushes me back to jog.

Try a hard 1.5 mile run.

No prob !  Yeah want a pace that feels fast but easy enough in the first 5minutes... 2nd 5minutes you start to wonder if its too hard, but seems maintainable... 3rd 5min feel tough, requires focus to not slow, but you got it!   lol at least that's how I usually feel during a good tempo run lol

Really want at least 10minutes , probably less than 20minutes... distance really isn't a component. 

For me 1.5mi isn't 10minutes...  for some it is more than 25minutes...

Well, I tried 2 miles in 30 min with a more constant pace but it is still not recording. HR is in 80% and above with no gps issue.

Constant Pace

Another thing I can suspect is that the issue started after I tried running with garmin coach. Will try pausing it and see what happens after a run

One thought that came to mind... do you have a weight entered in garmin connect?  need that to get a vo2max :-)  (and a maximum HR entered?)

I see a good steady run section from 3:30 to 14:30 then a little hickup and pace/cadence drop but holding on until around 17:00 , then a lot of either run/walk or something until the end.  That in my experience can cause issues with vo2max result.  What I would do is do as best you can to hold that steady strong hard pace (even getting to 85%+ max HR) most peoples threshold or lactate threshold or Tempo pace (workout efforts of say 20min steady, or long intervals of 2x 15min , 3x10min, etc) is usually 85-92% (towards the end of the workout or plateaus).  In my experience a higher heart rate for a longer steady period will trigger a vo2max result easier.

When you get to the part of run that you'd normally slow significantly or walk (min 17:00 lets say in this case.), stop the run on the watch and save it!  Then start a 'trail run' (no vo2max calc) and complete your run as planned or start a long cooldown, etc.  Should only take a few seconds while you catch your breath.

EDIT:  in looking closer I see that your HR did plateau at a peak in maybe the mid  or possibly high 180's - which is a strong effort even with your max of 197, that is well into the 90%+ range?  Looking at your cadence dropping throughout the steady 14min section.... i'd try to start the pace closer to how you finished that segment, so just a touch slower maybe.  Will allow a longer steady section, and hopefully also a HR that isn't peaking above 93% (?)