Why does Project move my tasks around when I assign a resource?


Some time ago, one of my colleagues came to me with a problem.  He was updating a MS Project schedule (plan) by adding resources to the project tasks and every time a resource was added to the task, Project would physically move the task up or down in the schedule.  This of course was very frustrating and wreaked havoc on the schedule.  For Example; Adding a resource to the task in the 4th row, would move the task to the 10th row and renumber the Work Breakdown Structure (WBS) number and the ID number.  It would also shift to another Summary task.  Not a good thing.

I am often a asked questions on how Project works.  I have used it for more than 20 years and over time I have become an expert.  I often say that Project is un-intuitive and this case is a good example.  "Why is Project moving my tasks around?" was his question to me.  "I have never had this happen before."  He added.

It took a while to find the answer.  As I usually do, I asked for a copy of the file and went off by myself to investigate.  I remembered that within Project one can sort on any column that one want to.  When I checked the file sure enough, someone had sorted the file on the resource column.  As resources were added Project would rearrange the tasks in Resource name order.  Once I resorted the file using the ID column, everything worked fine.  Resources could be added without changing the sequence of the tasks.  My colleague was very happy.  Here is an image of the fix.

First insert the ID column if it is not in the table and view.  Then click on the down arrow at the top of the ID column and select "Sort smallest to largest" option - circled below.  This will resolve the issue.

I offer this post as a help to other users of Project.  I have learned a lot of what I know about Project the hard way; by making mistakes and trying different things.  Project can be unintuitive, so remember that the learning curve is long and steep at times.