datatable not displaying fields

sarpratap

Hi,
We have a system that getting data from database using API and we use ajax to get data from api as json array and display it.
javascript file has datatable code from where it sending ajax request to php file which have api code to get data from database and that data is saved in json array which send back as response to display in datatable.

It works fine but some time it doesn't show us any data. Actually we do global search and send search string with ajax request.
What can be a problem here ?
Same data search if one user do then it shows data for them and for one user it not show any data.