Hi @Theresamarie1028
According to my understanding Advance invoice cannot be offset. Advance payments can be offset. You must receive a payment against advance invoice. The payment will be CUPIA transaction. Then you can offset positive CUPIA with a negative CUPIA.
have you tried to cancel advance invoice?
Go to Customer Orders/Invoicing of Customer Orders/Customer Invoice - Query for your Advance Invoice and RMB in the header to Create Credit Invoice. Once the credit invoice is posted the posting will be correct.
Further,If you have open debit and credit advance invoice and you offset them against each other, system is asking you if payments in advance need to be created. You have an option to just offset advance invoices without need of further payments in advance offsetting.
If this response helps you, please mark it as the correct answer, as it will also assist other community members in future.
Regards
Chanuka