TOC not working in particular book on 0.4

[a-singer]

I seem to think I saw something like this reported earlier, I even remember reporting something like it myself, and it was fixed, but I'm not sure, I may be imagining things. This book

https://wormhole.app/LOpmBl#l9_p2YG0pdJsdndfOJG9BQ

doesn't seem to allow me to go anywhere using the TOC. Enter does nothing. Hitting OK says

No Selection
Please select a section from the table of contents.

OK

Would you be good enough to have a look?

[trypsynth]

Aaaah I thought I fixed all of these, in fact I found another one of these before releasing 0.4 and thought we'd be good after that. Nevertheless, this is why we have users! I don't see why this is a problem right away, but it is the middle of the night. Will hopefully have a fix soon! Thanks!