Sometimes the parents of an individual don’t show up in People Workspace>Tree Tab>Tree but will show up in People Workspace>Person Tab. I usually notice this happens after I merge duplicate people. Thankfully there is an easy fix! While in People Workspace>Person Tab go to Relationships. On the right-hand side click the box next to “Preferred Parent”. This will connect the person with their preferred parents and they will now show up on the Tree.
How To Correct Tree View