Supplier Price List Lead Time

We are trying to update our Lead times on some parts in the Supplier Price List however some parts the lead time field is grayed out. If we log completely out of Epicor & log back in we can change. We have a coupld of people who are set up with administrator rights and they can change it each time. We don’t have any security set up down to the field level. Has anyone else experienced regular Users not being able to change this field at times?