Missed Badge

This was a challenge badge that you have to join.at the appropriate time. It's not automatically given for running 10K

And besides the challenge ended on August 9, and your activity is August 10.

Can you show me where did you see my workout was August 10?

I joined at this badge my dear

Just a thought, but if you edited the activity that might cause this issue. Usually this has no impact, but with some badges, if you change certain data like time or distance, that could cause the badge to not be rewarded.

To check for this, go to your activity on Garmin Connect Web. On the right side, under your device it will either say "Summary Data Edited" or "Summary Data: Original."

Can you show me where did you see my workout was August 10?

You posted your question on August 11. In that question you say "yesterday I have completed ...". "Yesterday" from August 11 is August 10, so I figured your activity was on August 10. Might be a misunderstanding, though.

What activity type are you using? It must be a running activity.