Wind directions not displayed correctly if not in mph

Windows 7 x64
German locale
WWL 6.1.12


please see this screenshot:

Wind conditions are being displayed correctly at the bottom of the screen where it says now and max. But at the upper right hand corner where the wind is being displayed graphically the display says “0” which is obviously wrong.

Problem is, if I set the wind to be displayed in mph everything is fine. If I have it displayed in anything else, like km/h, m/s or bft the graphical display just stays at “0” and also the wind direction is not given.