Custom fields values reverted back

Hi All,

I am facing an issue in EPM / Project Server 2010. 

When I update project property (enterprise custom field information) using PSI and update Project details using PDP.

Percentage of some project revert back from 100% to 99% and I am using of formula field it will become null after update project information as I mentioned above that either PSI or by PDP both.

Thanks & Regards, 

Haseeb Chishti