Unable to publish changes for estimate changes in AR plan when Time tracking has been set as the required field.

Issue Summary

Jira is unable to publish changes for estimate changes when Time tracking has been set as the required field.

Steps to Reproduce

1. Set the Time Tracking field as required.
2. Update the estimate field for any of the issues. 
3. When reviewing and saving the changes it fails.

Expected Results

It should allow to update the Estimate value for the issue

Actual Results

It fails with the below message:

Workaround

Make the time tracking as optional.