I had the same issue, my friend. I kept getting hit by it because I never expected it to hit high (plus a blockstring that switches guard like that is a bit tricky to deal with).
There wasn't any trick I came up with to block it either. Eventually constant trial and error drove it into my head. The only reason I can think of is that she's trying to force the T-shirt onto your "upper" body so it's a high block?