The gantt is unable to display tasks because there is more than one task with the same WBS sort value on this project.
To confirm that this is the case, the WBS Sort column can be configured on the Task List or the following query can be run in the datababe:
select i.code Project_Code, t.prwbssequence Dup_WBS_SORT, count(*)
from prtask t, inv_investments i
where t.prprojectid = i.id
group by i.code, t.prwbssequence
having count (*)>1
To reset the tasks WBS sort on the project tasks to where the sort value will be unique, there are three options:
1. Open the affected project in OWB and without making any changes, save the project back to PPM.
2. Open the affected project in MSP and without making any changes, save the project back to PPM.
3. Xog the affected project out ,and without making any changes, xog it back in to PPM.
4. Check if project has missing IDs for tasks
The tasks will now show on the PPM gantt as expected.
KB000029082: Blank Gantt / Missing Tasks for a project in PPM