Cannot complete sprint in next-gen project if a subtask is moved from an issue of active sprint to backlog

Issue Summary

Changing parent of a subtask is not updating the sprint value of the subtask. If the parent of a subtask is changed from an issue in an active sprint to an issue in backlog or future sprint, the active sprint does not get completed and throws "something went wrong" error.

Steps to Reproduce

1. Start a sprint
2. Add a subtask to one of the issues in the current sprint
3. Use the "Move" option for the subtask to move the issue under another issue in the backlog or future sprint.
4. Change the status of all the issues in the current sprint to "Done"
5. Try to complete the sprint.

Expected Results

The sprint gets completed.

Actual Results

The UI throws the error "Something's gone wrong" error

The below error is thrown in the console.

bundle.esm.js:60 Uncaught (in promise) Error: GraphQL error: Exception while fetching data (/completeSprint) : org.springframework.web.reactive.function.client.WebClientResponseException: HTTP 400 Bad Request. Error when calling https://atlassian-proxy.eu-west-1.prod.atl-paas.net/cloudid/e3bf75d6-dfd6-434a-9df8-29aba4f71789/jira/rest/greenhopper/1.0/sprint/600/complete: {"errorMessages":["Sprint cannot be completed as there are incomplete subtasks on following issues: OYEF-31"],"errors":{}}

Workaround

Temporarily move the subtask to a parent issue type and then finalise the sprint. Also, please use the "Change parent" option in the meanwhile to move the subtask as then this bug will not occur.

OR

A bulk operation can be executed to the affected Sub-Tasks in this state and update the Sprint field to its respective Sprint based on the parent.