background color is wrong when compiling with Xcode 9.0

I just recompiled my project using Charts 3.0.4. I did not change the Storyboard nor did I ever changed programmatically the background color of my CombinedChartView. Suddenly the background gets white (the color of the main view), my nice sky blue color of the CombinedChartView view is gone.

I checked to set the color to .clear after .initialize() but this results in a wired flashing black color. The only fix so far is that I explicitly set the background color to the desired value.

The same App previously compiled with Xcode 8 runs fine under iOS 11.

Update: just verified with iOS 10 same issue.