Error in deleting supplier address

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I just created a new supplier by using the copy feature and I want to delete the address code and create a different code.  I'm getting the below error but don't understand why as it is referencing Customer.  I created the account within the Supplier function, not BP function and there isn't any existing account under the customer.  We are at V12 and I don't recall ever seeing this error before.

any ideas?  

thanks C