ETC is reset to 0 on a Fixed Duration task when modifying task dates or duration

Products

Clarity PPM On Premise Clarity PPM SaaS

Issue/Introduction

When working with a task set to Fixed Duration in Clarity PPM, reducing the task duration or moving the task start/finish dates can cause the Estimated Time to Complete (ETC) on assigned resources to drop to 0 (zero).

This behavior typically occurs when an assignment is constrained to a specific date range (or a single day) within the original task timeframe, and a subsequent manual change to the task duration or dates shifts the active task window completely outside of the assignment’s scheduled work window.

Steps to Reproduce:

Create a project and add a task (e.g., Start: 01-JUL-2026, Finish: 31-JUL-2026, Duration: 23 days).
Mark the task as Fixed Duration.
Add a resource assignment with ETC (e.g., 184 hours).
Set the loading pattern to Fixed (or adjust assignment dates so work is concentrated on a specific range/day, e.g., 29th JUL - 31st JUL 2026).
Update the task duration manually to a shorter period (e.g., reduce duration from 23 to 10 days).
The task finish date pulls back (e.g., to 14-JUL-2026). The assignment date range now falls outside the active task window. Assignment dates reset to NULL, and the assignment ETC drops to 0.

The following table demonstrates how ETC is handled across various date and duration updates on a Fixed Duration task:

Step	Action	Task Dates	Task Duration	Assignment Start / Finish	Fixed Duration	Loading Pattern	Total ETC	ETC Distribution Behavior
0	Create Task	Jul 1, 2026 – Jul 31, 2026	23 days	—	Yes	—	—	Baseline task created.
1	Add Assignment	Jul 1, 2026 – Jul 31, 2026	23 days	Jul 1, 2026 – Jul 31, 2026	Yes	Fixed	184	ETC is distributed throughout the assignment duration.
2	Update Task Duration	Jul 1, 2026 – Jul 14, 2026	10 days	Jul 1, 2026 – Jul 14, 2026	Yes	Fixed	184	Task finish pulls back; assignment dates update to match the task span.
3	Update Assignment Start	Jul 1, 2026 – Jul 14, 2026	10 days	Jul 6, 2026 – Jul 14, 2026	Yes	Fixed	184	ETC distributes between Jul 6 – Jul 14.
4	Increase Task Duration	Jul 1, 2026 – Jul 28, 2026	20 days	Jul 6, 2026 – Jul 28, 2026	Yes	Fixed	184	ETC distributes between Jul 6 – Jul 28.
5	Shift Assignment Start	Jul 1, 2026 – Jul 28, 2026	20 days	Jul 27, 2026 – Jul 28, 2026	Yes	Fixed	184	ETC distributes between Jul 27 – Jul 28.
6	Reduce Task Duration	Jul 1, 2026 – Jul 14, 2026	10 days	NULL / NULL	Yes	Fixed	0	ETC becomes 0. Task finish moves to Jul 14, cutting off the assignment start (Jul 27). Assignment window is outside task boundaries.

Environment

Clarity 16.4.2

Resolution

This behavior is Working as Designed.

On a Fixed Duration task, the scheduling engine maintains the user-defined duration and dates. When resource effort (ETC) is applied, it is distributed across the specified active task window.
If an assignment’s dates are modified (for example, setting the Assignment Start Date equal to its Finish Date), the ETC becomes locked to those specific calendar dates.
When the task duration is manually reduced, Clarity automatically shifts or shortens the task's active finish date. If the assignment’s defined work window falls entirely outside the new task date range, the assignment loses its active window inside the task.
Because the task is set to Fixed Duration, the scheduling engine does not automatically recalculate, shift, or redistribute the existing ETC into the new task window. Since no work can exist outside the task's start/finish boundaries, the system resets the ETC to 0.

Workaround:

Use one of the following methods:

Manually re-enter the desired ETC values on the assignment within the new active task date range.
If no actuals have been posted against the task assignment, delete and re-add the assignment so Clarity automatically distributes the ETC across the newly defined task span.
If scheduling flexibility is required when changing task durations:
- Disable the Fixed Duration setting prior to editing dates/durations if you wish the task dates to dynamically adapt to assignment ETC.
Ensure task duration and task date range adjustments are finalized before locking assignments to specific single-day or constrained timeframes.

Additional Information

ETC on a Task with Fixed Loading Pattern is changed