When I put it in the header or footer, instead of processing to show that level title, I'm getting "<$levelNtitle>". Ergo, my interpretation of the bug.
I've tried the various auto-search and replace settings (both in compile defaults and on compile), and those don't touch it.
To replicate this error:
- Select something with multiple levels for Compile.
- Select a PDF format.
- Go into Edit Format… > Page Settings > Header and Footer Text.
- Use the "<$levelN_title>" in the header and/or footer area.
- You should then see "<$levelNtitle>" in the header and/or footer.