Google Chart not rendered on mobile

I tried to implement a chart with the following tutorial: Charts and graphs in SAP AppGyver(and creating Fiori-like dashboard) | SAP Blogs

But now I am stuck at figuring out why the chart is not drawn on my mobile (its just blank). The following variables look good to me:

And I assigned those variables to the chart component:

What is strange is that I can see my console logs are triggered executing the javascript but not the drawFunction.

Any tips on how to debug this further, other tutorials or hints what I did wrong?

Many thanks, Daniel