One of the items I keep in my traveling tool bag is a M8x1 stud created by cutting the head off an old crank bolt and filing flats on each side of one end. In the past, I've had problems with past extractions which involve a "female" threaded spindle, as the extractor can inadvertently smoosh the threads at the tip of the spindle, rendering it unusable. I thread in the stud about 10 turns/mm or more and then have the extractor bear on the stud instead of the spindle, which should eliminate the thread damage problem. It might have helped here in that the extractor wouldn't care about the washer as it would be pushing against the stud instead - unless the washer was preventing full seating of the extractor body, which can be a different serious problem.

Once a crank was so stuck that it destroyed the stud (and spindle) just before the crank arm hole threading let go, even after penetrant. But that was an exception that probably would have resisted all reasonable attempts.