Rstudio pandoc issue - r

Question

This example will knit on my laptop but not my desktop. Both are using the same RStudio and R versions. I have tried uninstalling R and RStudio, changing R and RStudio versions, changing 32/64 bit R, trying to install a variety of pandoc versions, setting the path to pandoc manually with Sys.setenv()... I am sort of at a loss here.
Both machines have the following:
> rmarkdown::pandoc_version()
[1] ‘1.19.2.1’
> version
_
platform x86_64-w64-mingw32
arch x86_64
os mingw32
system x86_64, mingw32
status
major 3
minor 4.3
year 2017
month 11
day 30
svn rev 73796
language R
version.string R version 3.4.3 (2017-11-30)
nickname Kite-Eating Tree
Here is a minimum non/working example. Again, it works on the laptop but not the desktop.
---
title: "Pandoc testing sandbox"
output:
html_document:
df_print: paged
number_sections: yes
toc: yes
toc_float:
collapsed: no
smooth_scroll: no
---
Here is a chunk of code to test:
```{r, results = "asis", echo = FALSE, message = FALSE}
tex2markdown <- function(texstring) {
writeLines(text = texstring,
con = myfile <- tempfile(fileext = ".tex"))
texfile <- knitr::pandoc(input = myfile, format = "html")
cat(readLines(texfile), sep = "\n")
unlink(c(myfile, texfile))
}
textable <- "
\\begin{table}[]
\\centering
\\begin{tabular}{l | c | c}
& without replacement & with replacement \\\\ \\hline
order matters & permutation: $\\frac{n!}{(n-k)!}$ & $n^k$ \\\\ \\hline
order does not matter & combination: ${n\\choose k}=\\frac{n!}{k!(n-k)!}$ & (\\textit{special case}) \\hline
\\end{tabular}
\\end{table}
"
tex2markdown(textable)
```
The error text on the desktop machine is:
Line 17 Error in knitr::pandoc(input = myfile, format = "html") :
Please install pandoc first: http://pandoc.org
Calls: <Anonymous> ... withVisible -> eval -> eval ->
tex2markdown -> <Anonymous> Execution halted
Any help with this would be greatly appreciated!
===
Edit: I did a bit more testing and ran:
rmarkdown::render("pandoctest.Rmd", "html_document")
And there was an option to "Rerun with Debug", so I did that, and the error is happening in "Function pandoc (namespace:knitr)" The line of code where the break happens in what I suppose is the pandoc function in the knitr package is:
...
if (Sys.which("pandoc") == "")
stop("Please install pandoc first: http://pandoc.org")
...
So it seems like pandoc is checking to see if it is installed itself? Or somehoe this is a pandoc function in the knitr package that is calling an actual pandoc program from somewhere else? SO it seems I need to get knitr to somehow see that I have pandoc installed.