Hi, I rarely post here but get a lot of useful infos that clarify some issues. Now it’s almost a month from your post. I hope you gotta an answer and work it around. If not, I’m afraid that I’m not bringing good news. Maybe I’m wrong, but here it is what I think that mislead you:
The Halion Sonic SE 3 that comes with Cubase 9.5 is not the same showed on the upgrade options. That one is Halion Sonic 3 - without the SE.
That’s why you don’t have any previous Halion license available to upgrade.
See ya!