I have reproduced the scenario following your advice: I set the Earned Value Method to “Physical Percent Complete” in the Advanced tab.

However, when I tried to update the progress, I noticed that the “Physical % Complete” field is read-only and cannot be edited directly.
Therefore, I had to update the standard “% Complete” field, which automatically updated the “Physical % Complete” to the same value.
Even in this scenario, with the Advanced setting applied, the problem persists: the Actual Cost is still recalculated based on the percentage, incorrectly showing 100 instead of 1,000.

What did I do wrong? Is there a specific step I am missing to decouple the input of actual hours worked from the physical progress?

The Scenario:
I have a task with the following baseline:
Duration: 10 Days
BCWS (Budget): 1,000 (e.g., 1 resource @ 100/day)

The Reality:
The 10 days have passed. The resource has worked for the full 10 days (so I have paid the full 1,000), but they have encountered issues and only achieved 10% of the physical work.

The Problem:
If I update the % Complete to 10%, ProjectLibre automatically recalculates the Actual Cost down to 100 (assuming only 1 day of Actual Duration). This is incorrect because I have actually incurred the full cost of 1,000.
I cannot manually edit the Actual Cost cell to correct this figure to 1,000 because the field is read-only when resources are assigned.

The Consequence:
My Earned Value analysis is wrong. The software hides the cost overrun.
Current (Wrong) Result: ACWP = 100, BCWP = 100. Cost Variance = 0.
Expected (Correct) Result: ACWP = 1,000, BCWP = 100. Cost Variance = -900.

My Question:
Is there a way to decouple “Actual Work/Cost” from “% Complete”? How can I input that a resource has worked/consumed 100% of the budgeted hours while the task progress remains at only 10%, without having to use workarounds like “Fixed Costs”?
Thank you for your support.