Room is made for the TOC along the left side, but only a horizontal line appears.
When I downgraded to rmarkdown 1.11, the TOC worked again.
install.packages("https://cran.r-project.org/src/contrib/Archive/rmarkdown/rmarkdown_1.11.tar.gz", repos = NULL,type='source')
This is reproducible, going back & forth between 1.11 and 1.12,
across my complicated app and a very simple example.
I thought this was the kind of problem that packrat is supposed to prevent... My buddy cloned my project with 1.10 in it, but apparently his rmarkdown 1.12 overrode packrat's rmarkdown 1.10. Anyone wish to give me a better understanding of packrat?