Search for issues associated with next-gen sprints doesn't return subtasks

Issue Summary

 If a user searches for issues associated with next-gen sprints, the search doesn't return subtasks.

Environment

Jira Software cloud

Steps to Reproduce

1. Create a Scrum next-gen project
2. Add stories to the project and add some subtasks to the stories
3. Create a sprint in the next-gen board's backlog and add stories which have subtasks to the sprint
4. Access the search page and search issues by the next-gen sprint name

Expected Results

All issues are returned, including subtasks

Actual Results

Only stories are returned

Notes

Workaround

Currently, there is no known workaround for this behavior. A workaround will be added here when available