Dear Joe,
The update process requires the following data:
1- Start/Finish actual dates.
2- Progress percentages.
3- Progress data date.
4- Run schedule from primavera.
When we import updates from excel, we update items number 1 and 2 above (which is the most time consuming process). Then we go to primavera to run the schedule and identify the data date.
hope my answer was clear for you.
Best Regards,
Hany Ismael