Relevant definition of fancy headers and footers for all pages, followed by redefinition of the footer for chapter pages:
\usepackage{fancyhdr}
\fancyhead[R]{\leftmark}
\fancyhead[C,L]{}
\fancyfoot[R]{\thepage}
\fancyfoot[C]{}
\fancyfoot[L]{\textit{\thesistitle}}
\renewcommand{\footrulewidth}{0.4pt}
\fancypagestyle{plain}{%
\fancyhf{}
\fancyfoot[R]{\thepage}
\fancyfoot[L]{\textit{\thesistitle}}
\renewcommand{\headrulewidth}{0pt}
\renewcommand{\footrulewidth}{0.4pt}}
If I use this without the second part (the redefinition of plain style), all non-chapter pages have the correct \leftmark (current chapter). However, if I add the bit concerning the fancyhdr for chapter pages, the command \leftmark gets ignored throughout the entire document.
Ideally, I want the \leftmark (current chapter) to show up in every non-chapter page, and have chapter page carry an empty header.
What am I doing wrong?

\thesistitletothesistitlefor the MWE. – Sep 16 '15 at 09:35\pagestyle{fancy}inside of chapter pages instead of before the document. – Sep 17 '15 at 02:51