Data model mismatch
Platform RealityCRM and ERP entities were never designed to map one-to-one. A Salesforce Account is a NetSuite Customer; an Opportunity becomes a Sales Order; field names, data types, picklist values, validation rules and currency decimal precision all differ. In multi-subsidiary NetSuite (OneWorld), the same company legitimately exists as separate customer records per subsidiary.
Records rejected on sync with validation errors, picklist values that arrive as blanks, amounts off by rounding, and reports in the two systems that disagree about the same customer.
A written field-correspondence map for customers, orders, items and financial records before build — including NetSuite's default mappings and composite match keys that include subsidiary. The worked mapping example in our Salesforce–NetSuite integration blueprint shows what that document contains.