I've spent some time making an informative vignette for an R package:
https://github.com/Robinlovelace/stplanr/blob/master/vignettes/introducing-stplanr.Rmd
It compiles fine in all the tests, but does not appear when I download it.
Test:
library(devtools)
install_github("robinlovelace/stplanr")
library(stplanr)
vignette(package = "stplanr")
Any ideas what's causing this strange behaviour? sure it used to work.