I'm surprised but happy to report that the door is now staying closed through several washing cycles! During the first few cycles we literally stood in front of the door to keep it closed while washing, and then we wedged a step stool to do the same. After 4-5 cycles run this way the door stayed closed on its own, and now I consider the repair a success! The only conclusion I can come to is that the heat from those first cycles might have "tempered" the new strike that I installed and caused it to stiffen and hold to the latch.