@XitThejaG I found a UPD13 patch that would 159758 resolve your issue. Therefore I suggest you to create a support case.
Test Steps :
# Create a Purchase Order -> Add a PO line
# Add a charge line with a Charge price with 7 decimals
# Release the PO order and create a PO change order
# Release the PO change order
# Go back to the Regional Settings and change the decimal places of IFS Currency Format to 3
# Restart application
# Go back to the Purchase Order / Charge Tab
# Try to change the Invoicing Supplier of the charge line
Note that the error message is prompted "The Purchase Order is associated to one or more Purchase Order Change Order (s). when using Purchase Order Change Orders, all changes needs to be registered on the change order and it is not allowed to register changes directly on the Purchase Order."
RnD Info:
Invoicing supplier is not a field that triggers a revision. In other words, there's no field in POCO to add the Invoicing Supplier.
Hence it should be allowed to save the Invoicing supplier in PO itself even when there's a an existing POCO.
The issue is not there in Part Order line or when the value remains the same before and after changing the currency format.