Bug - Axis Number Format

When I change the number format on an axis it is not applied to the chart

Description:

Create a "Line with Markers" chart from the following data
SS
Click on the horizontal axis and select Format Axis
Select the Number tab
Enter a new number format into the Format Code textbox
Press Close
Notice that the number format has not been applied
You must actually click on the Add button if you want to change the number format
This will add the number format to the list of custom number formats
<link to custom number format>

By default there is only one custom number format (#,##0;-#,##0)

Chart axes number formats and cell number formats are independent