I'm trying to create and view a flextable object in R or RMD. But even the simplest example is producing nothing but a large blank white image.

I've removed and re-installed the package several times and added "officer" and "officedown" packages but nothing is working. Thanks for any help anyone can offer.

library(flextable)
library(officer)
library(officedown)
library(data.table)

a <- data.table(x = 1:3, y = 4:6)
b <- flextable(a)
b

This produces a blank white image.