Incorrect Dates on Reschedule of Incomplete Work

[Karen]

I am updating a task progress as usual by entering an Actual Start date.
Since the task is incomplete, I specify the Remaining Duration and then
Update Project, Reschedule Incomplete Work to start after the status date.
When this is done, Project changes the Remaining Duration from the value that
I set to a lower value. This normally occurs if a task is set as Fixed
duration but in this case all my tasks are Fixed Units. If I then change the
Remaining Duration back again to the value I want, Project accepts the value
and shows the correct dates.
Why does this happen?

 

[Jim Aksel]

A fixed unit task will hold resource percentages constant. Since you are
indicating progress, MS Project will take [Remaining Work], hold [Units]
fixed and calculate a new [Duration] based on the unit's availability,
hours/day, etc.

Duration = [Work]/[Units Allocation] such as 16 hours remaining work
divided by one unit at 25% (2 hours per day) provides 8 days duration.

If you want, try making the task fixed work. Changing duration on a fixed
work will change resource units%