[RbnJrg]

Originally Posted by Vanguard3000

Here's a sanitized version of what I'm trying to do. It's pretty straightforward - just centred, 150% size, and upside-down, with a custom .ttf font. On the Kobo itself it looks exactly as pictured except the text isn't upside-down. The font, size, and justification are correct.

I don't know if you already have solved your issue but if not, then I think the cause if the custom font you are using. I say this because I didn't have any trouble to get the effect you are seeking. Try to exclude your custom font and only use:

.anclrg-ud {
   text-align: center;
   font-size: 1.5em;
   transform: rotate(180deg);
   -webkit-transform: rotate(180deg);
}

Watch the .kepub I attach.
Regards