Bug report
After the creation of an ad-hoc-subprocess I want to remove the colors to produce b/w-graphics for my lecture. After the change of the properties the ad-hoc-subprocess is a "normal" process (and the ~-icon is removed).
This is definitely an error.
But I can offer you a workaround for this. Create another normal sub-process and change the color, in your case to 'no fill'. Then use the functionality "Format Painter" (or "Format übertragen") - you find it in the toolbar - and transfer the color from the transparent sub-process to the ad-hoc subprocess just by clicking first on the sub-process and then on the ad-hoc sub-process.
I hope this will help. Best regards.