> Maybe its handy to hardcode a --clear statemenat if we run --sourceoff
it's not handy, - in general - if "clear" calling is neccesary then there is a bug. Such workarounds you suggest will hide the real bug.
I don't know if you understand how the hyperion priority stack works ... here a basic introduction:
(picture from wiki)
there several input generators. E.g. every effect, grabber or static color is a input generator. This genrates a list of colors per led (led colors). The led-colors are put into another list. The list has 2147483647 slots for led-color lists. When no specific input is selected, the first list of led-colors is shown. (first means the list with lowest index).
"sourceOff" simply means show led-colors in slot 2147483647 The is the last led-color list and it contains black values.
I can reproduce the behaviour you discovered. This is definitly a bug. When a static color is set input source switching wont work as expected. (regardless if you want to switch to "off" source or e.g. "grabber" source)