Unable to Dot-Walk using the Parent field for Project Tasks
This was happening due to customization of the "Parent" Dictionary Entry.
The Dictionary Entry was pointing to a custom table. It should point to the Task table (task).
Once this is fixed, I was able to properly Dot-Walk the Parent field and print out the Number. I used this Script to test in Scripts - Background module:
var sysId = '';
var gr = new GlideRecord('pm_project_task');
1. Navigate to System Definition > Dictionary
2. In the Table column search for "task" and in the Column Name column, search for "parent". Go to the record
3. Go to the Reference Specification tab
4. Change the Reference field from "Report Central" to "Task" (task)
5. Save the form