Issue Summary

The problem occurs during the Basic Search but not in the Advanced Search.
In the single-user picker field with project-specific context, selecting one user and then clicking the 'Search' button prevents the selection of any other users in the second attempt, resulting in a 'No matches' message even though the user is available in the dropdown options. However, during the first search attempt, multiple users can be found and selected simultaneously without this issue.

Steps to Reproduce

1. Create a custom field named 'Test Single User project' of type User Picker (Single User).

2. Create three test users

3.  Navigate to the Search Issue page. Under Basic Search, try to filter by 'Test Single User project'. In the first search, input the email addresses/username of the test users, and options appear in the dropdown for selection, as shown below:

4. Select a test user and click search
5. Try searching for another user by entering their email address/username to select them from the list.

Expected Results

The dropdown should include the matching users.

Actual Results

The dropdown shows ‘No Matches’

Workaround

Change the context to global  for the affected custom field 
OR
create a new custom field with global context for the purpose.
Please refer to Configuring custom field contexts