On v13 latest (odoo.sh). When creating Customer Invoice Draft (from settled Sales Order), the invoice lines and journal items are correctly display two products, the tax, and the account entries.
While in the Inventory, all previous steps are done for those two products. No pending receipts. Ordered products delivered to the customer. The remaining step is generating and posting the customer invoice and settle its payment.
However when I posted the customer invoice, somehow it generated extra invoice lines and journal items, apparently from Stock Interim accounts. This should not happen as I can't settle the payment due to differences.
I did Invoice Reverse and redo the steps, but the condition remains. Funny thing, the Reverse transaction has correct reversal lines and amounts (without the extras).
So I don't understand where those extra lines came from.
All the screenshots:
https://drive.google.com/file/d/1emHKfqTOY_w37CTRdYcJQgzt7qfUTE4p/view?usp=sharing
This is beyond confusing, it just doesn't make sense, either bug or totally wrong logics.
When I do Register Payment against this invoice, first, the display between the Customer Invoice screen and generated PDF are different. The former one: Total is 836.000 but Amount Due is 1.336.000 (with additional interim amounts added), while the latter one has correct Total of 836.000. Moreover there's another bug where the Payment Reference/Memo is strangely filled with one of the product description.
Second, about the Payment amount. If I fill 836.000 (as the actual payment should be), there will be Payment Difference of 500.000 (from total of the extra interim amounts), whether the invoice status will be kept Open or Fully Paid (with write off). Surely I shouldn't fill 1.336.000 for the sake of closing the invoice without the write off, because that later will not match with the cash received or bank transaction.
This is serious issue.
You should report this to Odoo.