SYMPTOM:
When the user performs copy/paste or save actions to a graph report, the following error occurs:

You do not have Use access to the GraphStyle object 'VerticalLine (9.0.1)'.

If the Everyone group with View access is removed from the ACL for "Children", the error occurs.
ACTION:
This issue can be resolved by adding the Everyone group with View access to "Children" back into the ACL of the "GraphStyles" folder.