I've noticed that whenever I jump off a cliff that has a small amount of land under it before water causes you go sink into the land and then you are unable to interact with water, i.e. with buckets/water flasks and the fishing action.
https://drive.google.com/file/d/0B19zfurT0IoYWFI0VFNTcm5WVzA/view?usp=sharing
heres a pic of what it looks like while there isn't interaction.
I've got it to happen when i've walked into the edge instead of jumping down, but also there were times it still worked when I walked into it.