Overview
Two distinct problems can cause a SKU's inventory data to look wrong:
- Zero valuation – the SKU has on-hand units, but every cost layer carries a $0.00 unit cost, so the SKU contributes nothing to your inventory value or margin calculations.
- Negative quantity – more units have been deducted (shipped, adjusted, or synced out) than were ever received, leaving the SKU with a sub-zero on-hand count in the system.
Both issues are fixable, but through different paths.
Part 1 — Zero Valuation
Zero valuation is covered in detail in the dedicated article Why do some SKUs show zero valuation and how do I fix it? That article walks you through:
- The most common root causes (receipts with no price, count adjustments without a cost, beginning-balance imports, etc.)
- How to spot affected layers on the Cost Layers tab of a product record
- Three fix options:
- Cost Layer Analysis on a single SKU (read-only preview, then apply)
- Nightly Cost Layer Rebuild setting for Weighted Average accounts
- Bulk repair job (contact support when many SKUs are affected)
Please read that article first if zero valuation is your primary concern.
Part 2 — Negative Inventory Quantities
Why Does This Happen?
Negative on-hand quantities can occur when:
- Over-fulfillment – more units are shipped than were recorded as on hand (e.g., a fulfillment order processed before a receiving report was posted).
- External WMS sync issues – a connected warehouse system deducts stock faster or out of order compared to Luminous.
- Manual adjustments – a stock adjustment was entered with a quantity that drove the balance below zero.
- Timing gaps – a return or receiving report was delayed, so deductions happened first.
What You See in the UI
The Inventory → Stocks page displays the true signed on-hand and available quantities — so a SKU with a negative on-hand will show the actual negative number directly. This means:
- Available quantity may appear as 0 even when pending orders exist.
- Reports and valuation may be understated or inconsistent.
- Cost layers may become out of sync with the actual stock position.
How to Fix Negative Quantities
Option 1 — Create an Inventory Adjustment Entry (self-service)
This is the recommended first step when you know the correct physical count.
- Go to Inventory → Stocks.
- Click New Inventory Adjustment Entry (top-right of the page).
- Select the affected SKU and warehouse.
- Enter the actual counted quantity in the New Quantity field. Luminous calculates the adjustment delta automatically (counted minus current).
- Save and post the entry.
Posting a positive adjustment entry brings the on-hand count back to the real physical count and writes an auditable entry in the quantity log.
Tip: After correcting the quantity, open the product's Cost Layers tab and run a Cost Layer Analysis to make sure the cost layers also reflect the updated stock position.
Option 2 — Resolve via the Inventory Discrepancy Report
If you suspect the mismatch is between stock quantities and cost layers (rather than a simple over-deduction), use the built-in discrepancy tool:
- Go to Insights → Accounting → Resolve Inventory Discrepancies.
- Review the table for SKUs where the System Qty (cost layer quantity) and Stock Qty differ.
- Select the appropriate correction type: Inventory Loss, Inventory Surplus, or Data Correction.
- Confirm to post the adjustment. Cost layers are updated to match stock quantities, and the change is recorded in the quantity log.
Option 3 — Bulk reset (contact support)
When many SKUs are affected — for example after a large sync event or a historical data import — Luminous support can run a bulk reset that:
- Finds every SKU with a negative on-hand count.
- Resets each one to zero and writes a corrective entry in the audit trail.
- Recalculates kit quantities that depend on the affected component SKUs.
After the reset, review your receiving history and create adjustment entries or run Cost Layer Analysis for any SKUs that still need an accurate count or cost.
Preventing Both Issues Going Forward
| Root cause | Prevention |
|---|---|
| Receipts with $0.00 unit price | Always enter a unit price on every Receiving Report |
| Over-fulfillment | Confirm on-hand quantities before posting large shipments |
| External WMS timing gaps | Enable real-time (rather than batch) stock sync where possible, or investigate sync delay settings with support |
| Count adjustments without a cost | Provide a per-unit cost when adding net-new units via adjustment |
| Recurring zero-cost layers | Enable Rebuild Cost Layers Nightly in Settings → Inventory Settings (Weighted Average accounts) |