Two users with same profile cannot see the same things

I have two users with the same profile and same permission sets assigned. One user can see a related list and one cannot on the Opportunity object. The user who cannot see the related list already checked her Display & Layout --> Customize My Settings for the Opp object and the related list is there. We've also checked FLS security on the lookup field (although it shouldn't matter since it is profile and not user-based and one user with the same profile and same permissions can see the related list) and verified that their profile does have access to the lookup field. Any thoughts? I am stumped.   #AwesomeAdmins