MWE:

documentclass{custom}

usepackage[utf8]{inputenc}



usepackage{amsfonts,amssymb,amsbsy,amsmath}

usepackage{tocloft}

usepackage{times}

usepackage{titlesec, titletoc}



%%titleformat{command}[shape]{format}{label}{sep}{before-code}[after-code]

titleformat{paragraph}[runin]{normalsize rmfamily}{theparagraph.}{1em}{}

titleformat{section}{centeringnormalsize}{ARTICLE thesection}{1em}{uppercase} %

titleformat{subsection}[runin]{normalsize rmfamily}{Section thesubsection.}{1em}{underline}[. ;]

titleformat{subsubsection}[runin]{normalsize rmfamily}{thesubsubsection}{1em}{}



renewcommandcftsecfont{ARTICLE uppercase}

renewcommandcftsubsecfont{Section }



begin{document}



%% tableofcontents % Works until I uncomment this line



section{Defined terms; rules of construction}

section{Organization of partnership}

subsection{Formation}

subsection{Name}

subsection{Certificates and licenses}

subsubsection{Optional}



end{document}

MWE output (using overleaf):

Notes:

Based on compile errors, the problem lies here I believe. Something to do with missing {}s.

titleformat{section}{centeringnormalsize}{ARTICLE thesection}{1em}{uppercase} %

titleformat{subsection}[runin]{normalsize rmfamily}{Section thesubsection.}{1em}{underline}[. ;]

Desired output (using overleaf):

Which I achieve unless I try inserting a TOC. Overleaf allows you to view this output with compile errors. But attempting to export to PDF via LyX you get: There was an error opening this document. The file is damaged and could not be repaired.