Hi, Row Id isn't the value you test for zero, it's the connector's unique identifier for the record, the API id GUID, which comes off the immutable SystemId. You use it to retrieve, update or link back to that line later, not to check cost.
The bigger problem, the standard API v2.0 salesOrderLines entity doesn't even expose Unit Cost. It gives you quantity, unit price, amounts, shipment quantities, related IDs, but no unitCost or unitCostLCY. So you can't just pick Sales Order Lines and build a condition on Unit Cost, the field isn't there to select. You'd need a custom API page (or a custom entity) that surfaces Unit Cost from the Sales Line before Power Automate can see it.
Also the trigger names, there's no "created or modified" one exactly. It's When a record is created V3, modified V3, or changed V3, that last one covers create/modify/delete together.
Glad to help - follow up if anything is unclear.
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Regards,
Grigorios Mavrogeorgis
Business Central Consultant & AL Developer
Work: Gmsoft Limited
Blog: insidebusinesscentral
LinkedIn: linkedin.com/in/gregorymavrogeorgis