The AR Invoice Batch transaction doesn't change once you post it.  What you're seeing is the original invoice transaction, not the current state of the transaction on the customer's account.  Go to Customer or Document Inquiry to see the current balance of the invoice.

The AR Invoice Batch transaction doesn't change once you post it.  What you're seeing is the original invoice transaction, not the current state of the transaction on the customer's account.  Go to Customer or Document Inquiry to see the current balance of the invoice.

Bingo

Okay, in Sage 300 I can go to Customer or Document Inquiry to see the current balance of the invoice.
How I can receive the current state of the Invoice using API?
Because method ARInvoiceBatches returns the original invoice balance.

ARPostedDocuments