Lily Pad disappearing when reeds\sugar cane are around

SSP
When messing with sugar cane, lily pads that cover the water around reeds sometimes disappears. I've been noticing this since 1.4.2. It seams seldom to happen both when plating or harvesting.

I've consumed at least half a stack of lily pads during the last couple of months, substituting those that went missing.

Here's a video:
http://www.youtube.com/watch?v=Z8loF0cUuO4

It's the only block I've ever noticed vanishing. I can reproduce this issue on every big-enough sugar cane farm i build.