Welcome to the community!
This should not have happened, as far as I can see. Questions:
- Is it only for
mpg? Or for any data? Try with iris.
- Is it only when you try
rmarkdown? Or, always? Open a new R session, both in RStudio and R GUI and check.
Can you run this and share the output? Solving this is beyond my scope, but someone who can will probably require this?
sessionInfo()