All good mate, I didn't feel offended at all.
Sorry I wasn't clear. I meant "dplyr does perform in-place modifications under the context of RMarkdown for temporary display only (see the RMarkdown picture of the result chunk under the code chunk), if permanent modifications are to be made, one should use the assign operator. "
That's why I said the two sentences and also why I said "dplyr does perform in-place modifications" because I am showing my example in RMarkdown with the output chunk under the code chunk. Anyway, it is not the point, and either the way whether I have used the assignment operator or not, it will not affect the HTML rendering and the HTML file should still be rendered. It is the strange part.
Thank you for your information. Sorry, I do not have an reproducible example..