At one point in time I was able to update my Marco Polo profile with my passport details so that when I had new bookings, the details would always auto populate. This was particularly useful for online checkin so you didn't have to re-enter passport details for online checkin.

I've tried to update my profile a few times now, and the passport details have saved in my MPO profile, but they never self-populate on new bookings. This is VERY annoying as I then have to re-enter the details on online check-in. Does this happen with everyone else?