Connect IQ 2.3.3 drawText with Transparent background problem when using own fonts

I have a watch face that works fine under Connect IQ 2.3.2 and uses its own font created with BM Font. When I use the standard drawText function after having previously called setColor function to set the foreground colour to blue and the background to COLOR_TRANSPARENT the text draws as it should. With connect IQ 2.3.3 the 'TRANSPARENT' background is now white.

Has anyone seen this issue ?

I have zipped up a simple watch face showing the problem. This sample works fine with 2.3.2 but fails with 2.3.3