Her flag sometimes bugs out and doesn't work at all - she puts it in the battlefield, but flag doesn't provides nor energy avatar nor accuracy bonus to your team.
It also seems just random at this point - happens about every 5th GW fight where I use her if I had to make a rought evaluation. I was tracking enemy comps but it seems useless.
The only thing you can be sure - if you had her flag bugged out while attacking on GW - it will occure on retry aswell.
Have never had this issue outside GS, but that could be the selective error as I don't pay attention to it anywhere else really.