I am having an issue similar to this post: https://support.rstudio.com/hc/en-us/community/posts/115007329208-Cannot-disable-inline-previews-for-Rmarkdown
As far as I can tell, I have set the previews to be disabled in every possible way under Global Options. I tried restarting RStudio and restarting my computer and was unable to get the previews to stop showing up.
R version: 3.5.0
RStudio version: 1.1.453
OS: Windows 7 Professional