Search result doesn't show sometimes on Fast order form

QUESTION: 

Giving some information first, I use Magento 2.3.4 and install the module Magento 2 Fast Order from your store and It works fine.

However, when I use ElasticSearch 6, on the fast order form, sometimes there is no search result even that product is set visibility.

Please tell me how to fix it?

ANSWER:

This error happens due to the fact that the module doesn't work with Elastic Search 6.

To resolve this issue, please edit the file as below or download the attached file and overwrite the current file on your site.

If there is anything else we might help you, please do not hesitate to contact us via https://bsscommerce.com/contact. 

We'd be happy to support.