I am sorry. I cannot make it fail consistently, until it starts failing, then it fails consistently. I am suprised no one else is experiencing it, but it is frustrating and I often just stop my work and move on to something else leaving family members unattached.
I do it a bit differently. I first go to the findagrave site and load the information in. Then I go to the parent or sibling and add relative (create profile) and then activate sourcer again to fill in the fields.
Because the new profile system creates an edit screen every time you create a profile I have multiple tabs open depending on how many people I am adding.
I genearally just keep adding and adding until I hit the people with no Find A Grave links.