In Data summary import only source.csv and verify four current working rows. Under Group summary choose currency as Grouping field and amount as Sum / numeric validation field, then run. Download and reopen CSV: USD/2/80, EUR/1/50, blank group/1/40; English headers are Group, Count and Total. Reconcile all four sources: 2+1+1=4, signed refund once, no combined original-currency amount. In a fresh page import blank-amount.csv, whose R03 amount is blank; the same sum must fail rather than report EUR0. Reimport the retained original to recover. A blank currency can remain unresolved; a blank amount is not zero. The separate hypothetical conversion gives 135 USD for three known-currency rows only, excluding R04; it is not a current rate or complete report total.
