Having the same problem. I did half a marathon and I did not get rewarded. But my performances are still recorded. I've noticed many people are facing the same issue, but the problem doesn't seem to move forward. I've seen a trick online which is to rename the activity to force the refresh, but that doesn't work for me.
I guess the watch measured a bit less then 21.0975km, which is the official length.
If you don´t pass this magic distance, it won´t count.
The same happens on the full marathon with 42.195km. You might correct the length in your activity manually. But I don´t know if this will count.
On that distances, it´s common to have slight aberrations. Garmin should be a bit more tolerant with that!
half marathon as a 13.2 km run
Huh? Half Marathon is 21.1 km or 13.1 miles.
Then I think Garmin has some inconsistency
The inconsistency is just with the badges you gained. If you look at the list of all available badges, there is a similar number of badges in km and in miles. And for example both Marathon and the Half-Marathon are labeled with miles, which is comprehensible since Garmin is an American corporation, and I guess US Americans are probably a quite important group for them.