I just got my December move goal award.

Have you checked every day just to make sure? Did you recently change to another of your Apple Watches? Sometimes when switching between Apple Watches it can take a few days for the move goal awards to start working properly, at which point all the missed ones will show up at once.I still didn't get mine, and I'm wondering why. I've achieved my Move goal every day in December.
Were you receiving the Longest Move Streak awards and did these continue after the glitch? When you complete your move goal today, check to see if you get the Perfect Week(Move) award.I've looked through the whole month, more than once, after completing my Move goal last night, and this morning. Nothing was missing. I'll take a look at it once more.
Afaik, I didn't switch watches in December. I'm using my new AW most of the times.
There was a glitch this week - the battery didn't even last a complete day. I had to force start it, which solved this, but it didn't affect my activities, afaik.
If the achievement awards were still there yesterday, maybe restoring your iPhone from yesterday's iCloud backup will get them back for you.I don't remember anything special happening on December 13th.
My iPhone is backing up to iCloud every day. The last encrypted backup to iTunes was at the end of October, so it's of no use in this case.
I force started my iPhone, which brought them back again.If the achievement awards were still there yesterday, maybe restoring your iPhone from yesterday's iCloud backup will get them back for you.
It could be. I've had activity awards stop and activity achievements disappear after an update before and had to restore the phone from the backup I made just before the update to fix the problem. This also meant re-pairing the Apple Watch. In your case, it would cause the loss of all data since the last backup from before the problem.I've sent feedback to Apple.
I've just noticed that iPhone and Apple Watch have been updated the day before I received my last "Longest Move Streak" award. Could this be connected to my problem, somehow?
I wouldnt know as I've never used iCloud backup.Ouch! I should backup my iPhone to iTunes more frequently. I guess the iCloud backup from December 11th won't be available now.
iCloud saves the last three backups.I wouldnt know as I've never used iCloud backup.
I suppose only the last few backups are saved?