I had created a scoreboard called treasureFished, which used the statistic, stat.treasureFished. I had been fishing for a very long time, got a ton of treasure items (name tags, saddles, bows), and the scoreboard never updated. I started to get impatient, so I looked in the statistics menu. None of the fishing stats were going up at all. I tried fishing in creative mode and in survival mode, but nothing changed the stats higher than 0. I have fished many items, but all the fishing statistics are always at 0.

I have not tested to see if any other statistics are broken, but I know for sure that the fishing ones are.