Hi Sean,
I'm not sure why my original code wouldn't work for you, I managed to replicate this in my environment and output all planned completion dates for parent tasks with 'Delivery' in the name using the code previously provided.
The way I would approach displaying the planned completion dates of parents that have 'Delivery' in the name, and child tasks that have 'Live Broadcast' in the name would be to create two separate columns and then link them into a single shared column.
Using the below code (pasted into the first column of my view) I am able to display all parent's with 'Delivery' in the name and all children with 'Live Broadcast' in the name. I've enhanced the expression to also include the task names in the view as well.
column.0.displayname=Delivery and Live Broadcast dates
column.0.listdelimiter=<br>
column.0.listmethod=nested(tasks).lists
column.0.sharecol=true
column.0.textmode=true
column.0.type=iterate
column.0.valueexpression=IF({numberOfChildren}>0,IF(CONTAINS("Delivery",{name}),CONCAT({name}, " - ",{plannedCompletionDate})))
column.0.valueformat=HTML
column.1.sharecol=true
column.1.textmode=true
column.1.value=<br>
column.1.valueformat=HTML
column.2.listdelimiter=<br>
column.2.listmethod=nested(tasks).lists
column.2.textmode=true
column.2.type=iterate
column.2.valueexpression=IF({numberOfChildren}=0,IF(CONTAINS("Live Broadcast",{name}),CONCAT({name}, " - ",{plannedCompletionDate})))
column.2.valueformat=HTML
Let me know how you get on, or if I can help any further.
Best Regards,
Rich.