[Cyber Liberty]

There was probably enough steam pressure and/or air left to make it work in that small volume.

Nope. Another way of looking at it is this: If pressure has anything to do with the siphon, why does the siphon work with the same (or negligibly different) pressure at both ends of the tube?

[BitWielder1]

The extra weight of the liquid in the longer leg keeps it going. We seem to agree on that part.
We in the pressure group maintain that the short leg of the siphon will stop working then the external pressure is insufficient to push the liquid up to the bend.
I'll allow a small extra height difference for the tensile strength, except for liquids like water that start boiling at low pressure.