Hello saarraa23,
The move and exercise rings are based an estimated caloric expenditure so it is odd one would work without the other. I know sometimes there can be a delay in the rings catching up so now that you have erased it you might need to wait a bit longer after your next exercise to see the rings catch up. If you used the Workout App to manually start a workout I guess maybe its possible you forced it to register exercise credit when it naturally would not have… maybe…?
This Apple Support article will walk you through the items it needs to know about you and settings needed to be able to make these estimates which would count toward closing the move and exercise rings. Get the most accurate measurements using your Apple Watch - Apple Support
Since you mentioned calibrating did you happen to run during calibration? It's possible that the watch is not counting the walk because during calibration you were exerting yourself at a high rate.
"Every full minute of movement that equals or exceeds the intensity of a brisk walk counts toward your daily Exercise and Move goals. For wheelchair users, this is measured in brisk pushes. Any activity below this level counts only toward your daily Move goal.” Which again brings up back to possibly forcing exercise measurement through The Workout App but I somewhat doubt that is possible.
Calibrating your Apple Watch for improved Workout and Activity accuracy - Apple Support
If you check all the info and settings from those links and it is still happening I believe the next step should be contacting Apple Support Get Support
I hope this is helpful,