Thanks for voting and commenting on this issue. Your feedback is key to helping us understand how you use JIRA so we can continue improving your experience. We have reviewed this issue over the last few days.
The Field Required Validator for workflow transitions has been incorporated into Jira Cloud as a native feature. For JIRA Cloud customers, we recommend using this validator as the most direct way to resolve this use case.
For Jira Server/Data Center customers, the validator is only available by installing the JIRA Suite Utilities plugin, which is a paid add-on on the Atlassian Marketplace.
Please don't hesitate to contact me if you have any questions or feedback.
Product Manager, JIRA Platform