Here is a jsfiddle using the same basic barchart code. With higcharts.js it works but with highstock.js the first bar is missing.
http://jsfiddle.net/LLExL/444/
Notice the first bar for january is missing though the label is there. It’s like the whole thing was shifted up until the first bar is off the chart.
I tried chart marginTop, spacingTop and xaxis maxPadding and reverse to work around the issue but all were uneffective.
The issue is fixed now, in this example the corresponding dev-version of highstock used instead of the released one (v1.0). Resulting in this chart: