Problem with Commission Junction Product Catalog Search Service (REST api)

Question

Having a strange problem with CJ's Product Catalog Search Service. Wondering if anyone else has encountered this?

The search below should return products from two of our affiliates, NewEgg and Overstock. We consistently see the NewEgg results, but the Overstock results only appear intermittently, maybe 30% of the time.

https://product-search.api.cj.com/v2/product-search?website-id=[CJ-WEBSITE-ID]&keywords=Flip+Video+U32120B+8GB&advertiser-ids=joined&currency=USD&manufacturer-name=Flip&records-per-page=10

The API call returns in a timely fashion for each request, so the query is fine and the api seems to be stable. I don't know why the resultset changes though.

Has anyone encountered this behaviour with cj.com web services and, if so, can you suggest a fix/workaround?