Rmarkdown knitr doesn't process code chunks when generating preview or html doc (and only shows code literals)

I checked to see if there was a settings for automatically executing the code, and found this previous post, but it looks like the settings are set correctly in my Rstudio instance.

link to previous post: https://forum.posit.co/t/automatic-execution-of-setup-chunk-in-rmd/71483/3