If Labelizer runs but custom labels are not updated in Merchant Center, the cause is usually access, feed setup, product matching, or the selected custom label slot.

Use this checklist to find the most likely issue.

Check whether the run was a preview

Preview runs (analysis-only) never sync labels to Merchant Center. The Merchant Center push step shows as skipped in the Status updates dialog.

If the run was started from the subscription dialog, it is a preview run. Upgrade to Core and run again to sync labels.

Check whether feed sync is enabled

Labelizer can be used to review results in Flowboost, but labels are only written back when feed sync is configured for the project.

Open the project settings and confirm that the Merchant Center and custom label settings are complete.

When label sync is disabled, Labelizer only writes to the custom label fields. Product titles and other feed attributes are never overwritten.

Check Merchant Center access

The connected Google user needs access to the Merchant Center account that owns the product feed.

If the Google user can access Google Ads but not Merchant Center, Labelizer may be able to calculate results but fail to update feed labels.

Check the custom label slot

Make sure the selected custom label slot is available for Labelizer.

Common issues are:

The slot is already used by another feed rule or workflow.
Campaigns depend on the current value in that slot.
A different Labelizer project writes to the same slot.
The selected slot is not the one you expected.

If you change the slot, run Labelizer again and review the output.

Check product matching

Labelizer can only update products it can match between the selected Google Ads account, Merchant Center feed, and project filters.

Products may not update if:

They are excluded by feed filters.
They are not present in the selected feed or data source. Products not found in the selected feed are silently skipped, which can cause a lower synced count than expected.
They do not have enough performance data.
They belong to a different Merchant Center account.
Their item IDs do not match the expected feed data.
They were inactive during the selected date range.

Check the latest run

Open the Labelizer project and review the latest run.

Look for:

Failed run status.
Warnings or errors.
A lower product count than expected.
No products in the buckets you expected to sync.

If a newer run started while an older Merchant Center sync was still in progress, the older sync is superseded and cancelled. Only the most recent run's labels are applied.

Check the Overview step. If the project shows Needs attention, resolve any configuration issues before running again.

See Run Labelizer and review results.