Can't pay AP invoice in currency different that invoice payment currency

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Hello,

We have an issue that we cannot pay an AP invoice in a currency different than the invoice payment currency.

And once the invoice is validated, we can no longer change the payment currency. Even if it is not yet posted.

The issue is that when the invoice is created, we are not sure in which currency it will be paid. Since it could be months before actual payment and at time of payment, the decision to pay this invoice in a certain currency would depend on which bank account has enough money to pay from it. And since payment is months after invoice, the period of the invoice would already be closed and reconciliation done. No changes are allowed on the closed invoice period.