Member of Site Admin group not authorized to edit/view channel entries

I maintain a multiple-site-manager installation of ExpressionEngine 2.9. We have a Site Admin member group that is used by our office admin staff to manage customer testimonials that are added as channel entries called Testimonials. An existing Site Admin (created before the affected account) is able to view and edit the channel entries, and a brand new Site Admin account I created was also able to. But at least one particular member cannot. Any idea what would cause this sort of issue?

EDIT: I used the login as tool to login to her account and it allowed me access to the Testimonials.