The way OWB works that is not normally possible.
A task can only be at the same outdent level a phases if the task is before the first summary level item in the WBS.
All tasks below the first summary level item are under a summary level item (Phase, Activity etc.)
There was a trick for a work around on the OWB site forum (RIP).
Another is to hack the db and a third is to edit the xml file for the project plan.
See for an ilustration (at the end)
Cannot See Task In Timesheet
15620322
Martti K.