Why won't durations parent rows in lower levels of multi-tiered hierarchy on project schedule roll u

Ty ✭✭
edited 12/09/19 in Smartsheet Basics

I have a project schedule with multiple levels of parent rows. In the Duration column, the 2nd and 3rd tiers of parent rows do not subtotal the children underneath them. Is there some other setting or consideration for getting this to roll up properly? Will Smartsheet allow a 2nd or 3rd tier parent row to subtotal the duration for it's children? Looking for some help to make this happen on my project schedule/gantt.

I've read all the articles that I can find on parent rows, hierarchies, etc. but could not find help o answers to this problem. Thanks in advance to anyone who can help!

[Please see screenshot where 3rd tier parent rows show either blank or zero duration.]

Screen Shot 2019-01-06 at 2.24.25 PM.png