Sometimes when a change is made to the Title and Properties section of a page, that change will not propagate down to the child pages. It doesn't happen all the time, but when it does, it usually occurs when a change has been made to either a Title or Description field in Title and Properties.
One workaround is to make a change to another field in Title and Properties (such as adding a space in the Social Media fields). This will trigger the proper behavior, and you should see your change inherited down onto the child pages.
