Quick question as I have received conflicting information about this:
when you use the vouchers to upgrade an economy class booking, is the booking class on the ticket then updated to J class? Last time I used my vouchers this is exactly what happened and the reservation looks entirely like a J booking in the app, I was able to select seats, etc

But I have also heard that for some people, the booking class was not updated and a "comment" (?) was added to the reservation that an upgrade was applied.
I think in this case I would be rather nervous that I will actually end up in J

Any experience with this? Thanks!