IRS are automatically initialized with the GPS position. However, the flight crew can override the automatic position initialization.
Not for all MSNs, depending on the software version, and unfortunately not for the incident aircraft.
Speaking as Boeing NG pilot; why would customer opt for (if that's the case) where the GPS position can not be copy/paste into the FMC for initialisation? Or why would a systems designer create that Gotcha?Punching in Lat/Long manual is an NNC an went out with Omega.