When creating a Work Order through Quick Create, the Billing Account is being set to the Account record and not the Billing Account from the Account.
Billing Account is set correctly on the Account but regardless of whether it is populated or not the Account Record is being inserted into the Billing Account field on the Work Order.
E.G. Test Address 1 has a Billing Account of Test Address 2 yet when I try and create a Work Order both Service Account and Billing Account have the same value.