The documentation (Configuring Time Tracking: About Legacy Mode) could have more explanation what users should expect when they turn ON legacy mode for time tracking.
It currently mentions:
- If Legacy Mode is disabled, your users will be able to change the Original Estimate value irrespective of any work being logged on an issue...
- If Legacy Mode is enabled, your users can only specify an Original Estimate before they start logging work on an issue. This value cannot be changed once any work has been logged, unless all work logs for that issue are first deleted.
Below information can be added to improve:
If Legacy Mode turned ON and in Edit issue screen:
- Remaining Estimate will be hidden/disabled; only Original Estimate being shown: if there is still no work logged on the issue. To avoid inaccuracy to planned time.
- Original Estimate will be hidden/disabled; only Remaining Estimate being shown: if there is work logged on the issue.