A warm welcome and thanks for posting on our community forums. This is strange why it is now showing on you on demand service. We have just replicated this request and all season 1-7 are showing on our on demand services.
Can you try again for us please?
Go to Home>On demand>Search type in NCIS and it will appear the 2nd or 3rd option down with all seasons.
If they do not appear, please reboot your box and re-try.
Kind regards Jodi.