My organization uses Project Web App integrated with Sharepoint task lists to share project plans and delivery schedules. Project Web App's Project Center has an aggregate timeline feature, which allows you to add tasks from individual PWA sites to a portfolio-wide timeline. This timeline is a fairly standard Sharepoint web part.
After editing the height of the timeline web part on the Project Center page (I wanted this to have a fixed px value...), I realized all of my previously added tasks and projects had disappeared from the timeline. Now, after I attempt to re-add a task or project, nothing actually appears on the timeline.
I've since reverted my changes to the height and rechecked all of the web app properties, but to no avail. I even tried creating a new Timeline web app-- no dice. Microsoft Support has been of no help--- even escalating to a PWA/Project Online/Project Pro specialist has warranted no fixes.
What can I do to bring back my timeline's Add Task functionality?