=ISNUMBER([@amount_text])
=IF([@amount_text]="","",NUMBERVALUE([@amount_text],".",","))
=COUNT(AmountSource[amount]) -> 4
=SUM(AmountSource[amount]) -> 35
=COUNTA(AmountSource[record_id]) -> 5
After paste as values, explicitly Clear Contents for the missing R5 amount; retain its row.