The pause at 1300 UTC in MickGo’s post ties in with the recent requirement for aircraft to hold off on the taxiway until guidance is available. Maybe the data is accurate maybe not? In a rumour forum that might suggest that the crew were waiting for guidance onto their bay.
600-ftlb said
You can't set the NIGS on 18A for a 737, the control panel won't let you.
which would suggest that the guidance that convinced the crew to carry on to the parking position came in a form other than NIGS. Pure speculation but it’s a possibility.