I may have discovered another bug within update 6.3.5 (new zoo update).
Last week, I realized that I was really close to completing the Lucky Chance IV achievement which requires playing 800 games at the House of Luck. I thought that I had remembered that I was at 780/800. I then downloaded the new update with the new zoo, and as part of regatta tasks, played the HOL 14 times. I checked my achievement again expecting that I would be only a few games away from finishing that achievement, but my counter was at 780/800. Even though it seemed strange to me, I thought that maybe I had been wrong about what my total was before.
Today, I played another 12 games at the HOL as part of regatta tasks. I just thought to check my achievement count again, and it still says 780/800. This time I know for a fact my total is not increasing.
I will include this in my ticket to customer service (I also have to contact them about the mining bug described here).
I am playing the iOS version, but it seems Android is affected as well per Graylady's post below.