When you use the search feature in the Point-Of-Sale, we limit the number of results to a maximum of 100 records.

If you have 150 products of candy and you search for "candy" then 50 of those products will not be displayed.
To get the correct results, please refine your search and be more specific to what you are looking for.

This applies to customers as well. If I have 150 customers with the first name of John or a last name of Doe, and I search for either "John" or "Doe"; I won't be able to see all of them.
To refine my search, I would then search for "John Doe". This will narrow down the results considerably. 

Searching for Products and Customer in Cloud Retailer - how to get more specific results video: