Sometimes I have all 3 pieces of sugar cane disappearing, meaning it has to be replanted. Normally the cane that disappears is random, not very often the same stalk. Sometimes it is here and there and other times it is long strips. Anyone else having this same issue?
As an explanation, one potential cause is the sugar cane and water being in different chunks. If the sugar cane is loaded in, and the water it depends on isn't, then the game simply thinks that that cane is there with no water, and pops off. It "disappears" purely because the dropped items despawn before you notice. I'm not saying that's what's happening with your case, but it can happen.
It's happening to me as well...sometimes only a few will disappear & other times the whole row disappears.
Whether it's fixed in 1.8 we can wait and see. But it can fixed by yourselves simply by making sure the sugar cane has water in the same chunk as it. Similar issues can happen with Cocoa Beans and Jungle Logs