I always use the bable (french) package and it works fine when one Overleaf or MiKTex. However, when copy pasting my code to Rstudio (with Sweave etc), it just does not work properly.
Document with "é" when done with Sweave
Same document (code copy pasted) on MiKTex
I have following packages:
\documentclass[a4paper, parskip=full]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[french]{babel}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{array}
\usepackage{tensor}
\usepackage{tikz}
\usepackage{graphicx}
\usepackage{verbatim}
\usepackage{enumitem}
\usepackage[abbrev,backrefs]{amsrefs}
\usepackage{appendix}
Since I don't know much about Rstudio, I don't know what information you need about it. I will provide more info when asked for. I followed a simple tutorial on youtube to get sweave working.
Thank you.
Edit:
Here is a minimal document. (not sure how to link the whole pdf)
The code in Rstudio (Sweave) is following:
\documentclass[a4paper, parskip=full]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[french]{babel}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{array}
\usepackage{tensor}
\usepackage{tikz}
\usepackage{graphicx}
\usepackage{verbatim}
\usepackage{enumitem}
\usepackage[abbrev,backrefs]{amsrefs}
\usepackage{appendix}
\title{Année académique}
\date{}
\begin{document}
\SweaveOpts{concordance=TRUE}
\maketitle
This is a sentence with the characters é and è.
\end{document}