I have the same situation. Maybe it calculates it on a basis of 24h. With a new location it probably has to run 24h before the 0.00 changes. That is what I’m thinking not sure if it’s correct.
Problem fixed:
there is a cron script doing average on latest data, and the result is used for the map icon
that script lost its executable attribute, and got lots of permission denied errors when running
something I was unaware of.