Product Attribute Data Is Not Synced To Klevu Indexes
Problem
Attribute data for product records is not showing in Klevu indexed data
Potential Causes
Attribute Is Not Registered With Klevu
If an attribute is not registered with Klevu before data is sent, the request will be considered invalid and the payload will not be processed.
If this is a standard Magento attribute, first of all ensure that the Register with Klevu setting is enabled in the Manage Attributes page (Stores > Attributes > Product)

Next, you can check which attributes exist at the Klevu side for any integrated API key by visiting the Klevu Information section (Stores > Configuration > Klevu > Information > Indexing > Attributes > Klevu Attributes)

Product Has Not Been Synced With Klevu
You can easily check the last sync activity for individual records via the Magento products grid (Catalog > Products). In each product row, under the “Select” dropdown in the Action column, you will find a “Klevu Sync Info” link.

Clicking this link will show all recorded sync activity for that record across all integrated API keys.

There are a number of reasons a product may not be picked up for sync which are out of scope of this article. If running entity discovery / update and triggering a sync does not send the record, please contact our support team for help.
Product Synced But Rejected Or Dropped By Klevu Indexers
If data is being included in the indexing API payload but doesn’t appear in the indexed data in Klevu, there may be issues with the data itself, or issues with other products within the same batched payload.
In the Entity Sync Information screen (shown above), you can see the status of each sync attempt which included this record. If sync is not being performed successfully, please enable verbose indexing logging (Stores > Configuration > Klevu > Developer Settings > Logging > Indexing Log Level); trigger a sync; and contact our support team with the relevant log file(s) for help.
Product Synced Successfully But Does Not Contain Attribute
If product records are being received successfully by Klevu’s indexers, you can validate the payload sent to the API by enabling verbose indexing logging (Stores > Configuration > Klevu > Developer Settings > Logging > Indexing Log Level); triggering a sync; and checking the resulting indexing log file (at var/log/klevu/{storeCode}/klevu-{storeCode}-indexing.log).
You are looking for DEBUG lines containing the string “Chunked payload”, which will contain the request payload in the context

If the attribute code is not present in the payload, ensure that the pipeline configuration contains the relevant extraction stage(s) for this attribute.
The following command in the Magento CLI will generate a dump of the entire product add / update process. In our example, we write the output to a file in the var directory, as pipeline configuration can contain thousands of lines.
$ bin/magento klevu:indexing:configuration-dump-pipeline KLEVU_PRODUCT::add > var/KLEVU_PRODUCT.add.ymlIf the attribute code is present, please contact our support team for further help, including both the indexing logs and generated pipeline configuration.
If the attribute code is not present, or only present for a subset of products, ensure that automatic pipeline generation is enabled for this attribute via Stores > Attributes > Product and checking the Automatically Generate Pipeline Configuration For setting.

You should see every product type that should contain this attribute data selected. If any are missing, update the field configuration and save the attribute; and then trigger entity update and sync operations, which should now contain the missing attribute.
When managing attribute configuration, we need to both register the attribute with Klevu so that the receiving end expects this data and knows how to process it, as well as including this data in the payload we send across.
We do not automatically assume you will want to sync attribute data for any product type in order to provide you with as much control over your data synchronisation as possible. For example, you may explicitly not want to send data for certain product types (one use case would be excluding configurable parents to avoid potential unwanted data inheritance); alternatively, you may wish to define your own extraction; transformation; and validation stages (as detailed here: Changing Attribute Data Sent to Klevu IndexesChanging Attribute Data Sent to Klevu Indexes - Klevu Magento v4 )
If the attribute is still not present in the payload following these changes, please contact our support team for further help, including both the indexing logs and (re)generated pipeline configuration.