Epicor P21 SISM 'Item ID Not Found in inv_mast': Resolving Missing Customer Part X-Refs

Automated Fix & Pricing (`OrderAirlock`): Starter $249/mo ($2,490/yr annual, 500 POs/mo) · Distributor/FDE Pro $499/mo ($4,990/yr annual, 2,500 POs/mo) — quarantines unmapped buyer SKUs at Gate 2, binds customer aliases in 1 click, and outputs valid P21 inv_mast item_id rows.

Direct Root Cause & Fix: When a contractor PO lists the buyer's internal part number (MECH-VLV-200) in item_id and no P21 Customer Part Cross-Reference exists for that customer_id, SISM aborts the entire order import. Resolve (customer_id, raw_part_no) -> inv_mast.item_id upstream before writing the SISM drop file.

Why Maintaining X-Refs Only Inside P21 Breaks Down

• Contractors change procurement software (ServiceTitan, Procore, Coupa) and emit new part prefixes on Friday afternoon rush orders.
• One unmapped line out of 45 lines blocks the other 44 in-stock lines from reaching warehouse pick tickets.

Deterministic Resolution Flow

1. Evaluate each PO line in strict precedence: customer_alias_rule (customer_id + raw_sku) -> exact inv_mast item_id -> UPC/GTIN.
2. Quarantine only unresolved lines with side-by-side PO bounding-box evidence.
3. Persist the alias rule on resolution and emit item_id=<internal_sku> alongside customer_part_no=<buyer_sku> in IMPLNE.