Originally Posted by
mccartje
Only the "immediate-upgrade" via cash should earn you extra tier credits and avios. Using Avios to upgrade will still only net you the original economy fare tier credits and avios similar to the bid system in this case.
Many thanks!
And is instant-upgrade only via Manage My Trip, either on the app or website? Meaning it's not shown, then it's not possible--and it's certainly not
this? I have a mileage ticket and Reddit seems to suggest you're SOL in that case--they can't or won't upgrade those.