Do you have any other Case link in the navigation like I showed in you in the above screenshot? If you have not customized/removed the account form then you already have a subgrid called Recent Cases..if not add a subgrid and see if the records are available.
I have experienced this issue and it was always the wrong relationship.
Also, navigate to any of the existing case and then from there click on the account, it is possible that you have multiple account record with the same name.
Hope this helps.