AVG Resting Heart Rate Setting

Hey 

when setting my RHR on watch as “use avg” the watch does not keep this - it always jumps to 55 after 1-2 days 

which in fact is the heart rate set in garmin connect when you go to “set as %HRR “ 

wouldn’t it make sense to add the option on garmin connect to use avg RHR for this not a fix RHR ? 
is this a bug ? 
bests