Sage 300 V2014 PU3

Client was creating and copying Price lists.

We now find that the Customer Type on the Customer Record > Invoice Tab has

- no longer has the "Base" option

- still has options A B C D E

- has a new option at the bottom called "Insert optional field"

Now when doing a sales order all the settings are one out as it now takes A as Base, B as A, etc.

WHAT could have caused this and how do we get it back to how it should be.