Unfortunately, partial matches aren't supported due to Shopify limitations.
Starting from December 16, 2019, our app uses Shopify API 2019-10, where requests that pass a value for the title match only if the value is the same as the complete title.
Example: Your product title is "Cherokee Boys Grey Melange Track Pants". So you should search by the complete title "Cherokee Boys Grey Melange Track Pants" to get a result, not by a partial text "Cherokee".
In the meantime we are searching for solution, so please wait for update patiently.