The standard related record list for opportunity is not visible for a user who is having read permission on opportunity look up field present in Case object and also have read,create,edit permission on his profile for opportunity object. the user is getting the error message "We can't display this information because the record has no parent or you don’t have access. Ask your admin for help." But the user is able to locate the opportunity record via the lookup field present in case lightning page. Attaching the error and expected result of screenshot for reference.