What's wrong with my curveball?

So I've got pretty good at landing curveballs. Well, according to How to throw a curveball that's what I think I'm doing. But I never seem to get the 10xp bonus for curveball, whether I hit inside the target or not (in my example I happen to get a great throw).

I know for a fact the curveball bonus stacks with the others, so what am I doing wrong?

Update August 8th

Curveballs seem to work only by themself. They still don't stack consistently.

Curveball + Throw Bonus yields only the Throw Bonus

Curveball by itself yields only the Curveball Bonus

Update July 31st

This seems to have been partially fixed. I am consistently getting 10XP bonuses for every curveball. However.. it seems now if you throw a curveball with a Nice! Great! or Excellent! throw you only get the curveball 10XP. Seems Niantic just can't get it right, can they?

This seems to be exclusively a game problem.

Once the Pokeball is spinning as I showed in my question, that constitutes the 10XP Curveball bonus. However, according to a few people in the comments, the curve ball bonus gets awarded with normal throws as well.

Over the past couple days I kept my eye closely on my bonuses and noticed I did get the 10XP Curve ball bonus once or twice, proving that the bonus is still in the game, however broken — completely.

I have yet to get the Cureball Bonus along with a Nice/Great/Excellent throw bonus, but until proven otherwise this has been shown to be in the game.

At this point I am certain you cannot get that bonus reliably. I'm not sure if it's a bug the exp bonus got removed.

I've been throwing almost exclusively curveballs for the last 2 days, because I found out about the exp bonus and wanted to get used to landing them. I made a lot of catches with curved throws: most didn't get "great" or "nice" bonuses, few did, I even landed 1 curvebal on a jumping pokemon.

I couldn't get the "curveball" exp bonus even once. My friend had the exact same experience, although, he wasn't focusing on cureballs only.