are you using annotations for amount and currency code something like this:
{ bpa.bp_id as customer_id, bpa.company_name, @Semantics.currencyCode: true so.currency_code, @Semantics.amount.currencyCode: 'so.currency_code' ( so.gross_amount - so.net_amount ) as tax_amount, @Semantics.amount.currencyCode: 'so.currency_code' 0.85 * cast( so.gross_amount as abap.fltp ) as reduced_gross_amount
}