Why is the Bill To Address not visible in iStore

We are on 11.5.10.2. There are a couple of iStore users who are not able to see/select Bill To Address. The Customer Account has valie active primary bill to address. However, when I looked in one of our older instances, I saw that the Primary Bill to address was updated - the Primary and Active boxes where unchecked in April 2013, which was the last order that the iStore user was able to process on the store successfully. The Bill To address have been updated i our production database since them - the primary and active boxes were cheked/enabled on