By "non-expiring", does this case refer to the pre-2014 tickets that had the non-expiring option?
(We had, in another thread, worked out a term for pre-2017 tickets that were non-expiring if unused, if only I could remember what we decided to call them.)
It's hard to imagine why the pre-2017 couldn't be upgraded, as they still exist, just with a tiny change in terms, so I'm guessing your tickets are the older ones.