I killed few whales (both kinds). And I waited for about 7 days so I could hack them. When I sailed to them, everything was ok, I could hack it, no more waiting. But when I hacked each one of them, it always exploded and I heard the splash sound but I got nothing from them. No loot, no meat, just nothing. I tried to sail around in a bigger circle, but still nothing.
This problem has appeared after the Eye of the Tiger Shark update. In Hang Ten was everything fine. I don't play with some custom character.
Killed one of them with arrows(mod), another with blow darts, another with machete and so on. Seems no connection of bug with type of weapon. I tried also to spawn some whales by a console. Still same result. Tried also let it be for so long that it'll explodes by itself. Still nothing.