Summary

When a user types a few keywords on the search box for the custom field type  (Text Field (single line))in the list view, then it doesn't display issues and sometimes it displays multiple issues for Jira project as shown below in the screenshots.

But if we type the full keyword in the search box, it displays the issue in the list view:

Environment

Jira Cloud

Cause

This is the expected behaviour as the search in the list, timeline and calendar view is done via JQL.

Solution

 If we pass in 993 in the search box, the JQL we send becomes:

text ~ 993* 
The * at the end means we apply fuzzy search, but only in that direction (after the search term typed, not before it). Therefore it is an expected behaviour in the list, timeline and calendar view search.