Waterfalls and lavafalls will occasionally not render the top face. It seems to happen more frequently when the face is at a steeper angle, as seen in the screenshot.

Notice the taller falls in the middle and left showing the issue, while the smaller fall on the right does not.

Thats allready a known bug and will be fixed in Sodium 0.2.0.
Its the fancy translucency bug you're describing :)

Nice to know. Thanks and sorry for the duplicate issue.

To clarify: the issue pictured here is not the lack of vertex sorting that Erazer750 is talking about, which is planned to be fixed in Sodium 0.2 and tracked in #38
Instead the issue pictured is incorrect culling of the water's faces based on the angle the chunk is viewed at.
This problem has already been fixed by 5840ca2

Re-opening until merged into stable

I was planning to create a new issue but I found this issue. The title confuses me a lot.
It wasn't only the top, but also the side ones. From my understanding when one of the sides of the water shares the same pixels as the dirt behind, sodium decides not to render it.

Fixed with 772893d.

This issue still occurs in some situations even after commit 772893d.

Seed:
-6705514674227345575

Location:
/tp @p -409 67 110 120 -26.6

Reported by BinaryBreakpoint on the Discord, I've confirmed it.

"BinaryBreakpoint" is using windows and in minecraft they use a FOV of 30.