Issue with natural indentions for enumerate

Question

Following this post, I have attempted to remove the natural indent for enumerate/itemize. To my dismay, it's not entirely removing the indent. How do I fix this? The following is a minimal working example:

\documentclass{article}
\usepackage{enumitem}
\usepackage[margin=1.20in,showframe=true]{geometry}

\begin{document}

\noindent\textbf{\large Problem 1}
\begin{enumerate}[leftmargin=*,label=(\alph*)]
\item 
\item 
\item 
\end{enumerate}

\end{document}

It produces the following:

Answer 1

Use the wide option of enumitem. This way the lavbels will be left-aligned along the left margin of text (which is different of left margin of the list):

\documentclass{article}
\usepackage{enumitem}
\usepackage[margin=1.20in,showframe=true]{geometry}

\begin{document}

\noindent\textbf{\large Problem 1}
\begin{enumerate}[wide = 0pt, leftmargin=*,label=(\alph*), start = 12]
\item Test text test text test text test text test text text test text test text test text test text text test text test text test text test text text test text.
\item Another tongue twister. Another tongue twister. Another tongue twister. Another tongue twister.
\item
\end{enumerate}

\end{document} 

Answer 2

The \alph* enumeration labels set a width that's enough for accommodating “m”, the widest letter.

You can solve simply the issue by adding align=left:

\documentclass{article}
\usepackage{enumitem}
\usepackage[margin=1.20in,showframe=true]{geometry}

\begin{document}

\noindent\textbf{\large Problem 1}
\begin{enumerate}[leftmargin=*,label=(\alph*),align=left]
\item Prove that $1+1=2$
\item Prove that $1=0$
\item Conclude that $1=2$
\end{enumerate}

\end{document}