Grazie,
Not to beat a dead horse, but whenever I get the blinking w, I know I don't have a good white balance. Subsequent footage has not been to my liking. However, I've always been able to get a solid lock by focusing on the white target and exposing as best as possible. Works every time....so far. BTW, I use the Warm Cards white backside almost exclusively but in hectic situations, I'll use a white wall or tablecloth, etc.
Bob