I didn't find a way to do the grouping without activating the sheet where you do the grouping in. the proposed solution to replace selection with row works as long as the sheet you are doing it in is active or selected.

In my case I want to split up my data into 2 sheets and do some grouping and formatting. I can insert rows, copy formatting from my sample format to each line and everything without usage of any selection, just the grouping requires me to select the sheet and thus will cause the screen to flicker.

I did switch off screen updating already, but it would be much nicer