I have a task that is 138 hours with a duration of 215 days, from 5/8/18 – 3/12/19. It is fixed duration and not effort driven. When I look at capacity for the assigned resource (only one assigned), the distribution of hours is 0.08 from 5/8/18 through 2/19/19 and then the hours bump up to 8.28h per day from 2/20/19 through 3/12/19. To date, no time has been assigned to this task, so remaining hours are still 138, but I still want the hours to be evenly distributed across the entire duration of the task. I tried fixed work to, and that didn’t work.
I tried to reproduce your situation, but failed. I created a new task in a new project schedule and entered the Start and Duration. I switched the task to Automatically scheduled and set the Task Type to Fixed Duration. I assigned a resource and modified the Work. Work is evenly distributed when I check it in the Task Usage view.
Marcel is correct. It can be very difficult to reverse engineer why something happened with project work. If no actual work has been entered to date, the best option I can think of is to remove the assignment and re-enter it again. That’s more complicated if actual work was entered. Hope that helps…