VO2 no longer showing after walks

I have used my watch for many walking activities and it has never recorded a vo2max.  I wasn't aware that it would, until recently from a post from Garmin or FirstBeat about how the algorytim works and ranking of how it uses the different activity types.  

I believe if it has recorded a vo2max for running, it won't use the walk calculation for awhile iirc.  Which makes sense as running will give a much better representation of what someone's maximum oxygen intake is per body weight as it is a higher effort activity, closer to your vo2max effort.  Even while running it won't give a vo2max reading update for me unless my HR is above zone1 Heart rate it seems most of the time.  Which also makes sense, if it is too easy it can't accurately extrapolate what my high end fitness level is.  Same for a walk that would also be typically a low intensity effort for most people.

Here is an interesting article from Garmin explaining some eof it, but not maybe all of it.  I am looking for the forum post about it.  

https://support.garmin.com/en-US/?faq=lWqSVlq3w76z5WoihLy5f8

https://support.garmin.com/en-US/?faq=HVMcrDvQ3m2xEFh1aVMbU8 (HAS NOTES ABOUT NOT TRUMPING A PREVIOUS GOOD READING with subsequent "OK" readings... )

quoteing site: 

The Type of Activity Recorded Did Not Trump a Previously Recorded Activity

The type of activity you complete can determine if you will receive an updated VO2 max estimate. Your overall VO2 max estimate is taken based on the following four activity types, listed in order of preference based on their accuracy. The most accurate VO2 max estimate will display in Garmin Connect and will overwrite less accurate methods for 30 days. Not all Garmin products support all methods of VO2 max estimation.

NOTE: If you complete a qualifying cycling activity with a power meter, a separate Cycling VO2 max will populate. The Cycling VO2 max will update each time you meet the Cycling VO2 max estimate criteria.

1. Running Activity With GPS

This activity type yields the most accurate overall VO2 max estimate and will trump all other activity types.

Example: You record a Run activity with GPS, which generates a VO2 max estimate. This VO2 max estimate will display in Garmin Connect and will only update over the next 30 days if you record additional Run activities with GPS. Other activity types below in this list will only update the overall VO2 max estimate when the most recent Run activity with GPS is older than 30 days. 

2. Walking Activity With GPS

Example: You record a Walk activity with GPS, which generates a VO2 max estimate. The next day, you record a Run activity with GPS, which generates a VO2 max estimate. The overall VO2 max estimate in Garmin Connect will be updated regardless of the age of the Walk activity because Running activity with GPS is #1 in this list.

3. Walking

This applies to walking done during daily routine without recording an activity.

4. Running Activity Without GPS (Using Foot Cadence as a Speed Estimate)