and incorrect rendering of missing values

I have a flexdashboard with shiny components that I've published to

When I run the document locally, missing values in the tables appear as "—" (see below).


However, when I publish the document to, the missing values appear as "<97>" (see below).


I have tried specifying the missing values as NA with na_if() but I get the same outcome and I have also tried specifying "—" as na.strings when I created the table:

data <- read.table(text = readLines("file.csv", warn = FALSE), header = TRUE,sep = ",", stringsAsFactors = FALSE, na.strings = "—")

Is there any way to specify how missing values should be rendered upon publishing of a .rmd file? What trick am I missing?