We have a User who can not see related list of the Opportunity (Classic and Lightning both) though he owns few records if not then he is there as Sales team member in Opportunity. He is getting an error message as 'No Related list to Display'. Opportunity is Private in OWD. We don't have any permission sets. Now the main twist is - Other users having the same Profile have no issues and they can see the related list. Amazed what is missing for that User as the Users with the same role & profile does not have any issue. If anyone has any clue please let me know.