2608424 - Exchange rate greyed out in app Create Outgoing Invoices/Create Incoming Invoices

In "Create Outgoing Invoices" or "Create Incoming Invoices" app, wishing to edit the exchange rate in the 'Local Currency' section of a foreign currency invoice, but the value appears greyed out and not available for input. 

Image/data in this KBA is from SAP internal systems, sample data, or demo systems. Any resemblance to real data is purely coincidental.

Example with app "Create Outgoing Invoice", same principle applies to app "Create Incoming Invoices".

1. Open app "Create Outgoing Invoices".
2. Enter header details including Company Code, Posting Date, Customer, Foreign currency, etc.
3. Item values also entered.
4. Select the 'Local currency' tab the 'Exchange Rate' field is greyed out. 

The 'Exchange Rate' field cannot be changed after line item(s) are entered.

To change the default exchange rate, this must be done before entering the items.

1. Open app "Create Outgoing Invoices".
2. Enter header details including Company Code, posting date Customer, Foreign currency, etc.
3. Press Return.
4. Select 'Local Currency' tab, now Exchange Rate is editable.

Local Currency, Cloud, Create Outgoing Invoices, FB70, FB60, Create Incoming Invoices, Greyed, Exchange Rate, Editable , KBA , FI-FIO-AR-2CL , Fiori UI for Accounts Receivable (Public Cloud) , FI-FIO-AP-2CL , Fiori UI for Accounts Payable (Public Cloud) , How To