Biblatex-chicago showing a line instead of names in bibliography for some entries

Question

This is a followup to the post BibLaTex and citing same source several times in same paragraph. When I compile my document, my bibliography sometimes exchange the name of the author with lines. One of the entries that had a line instead of the name in my original document, has name shown here. In my previous problem (linked above) the solution was a simple "switch". I have looked for the solution in the manual, but I probably do not understand where it is mentioned.

Sorry about the long MWE, but it felt necessary to add all the bib-entries to show my problem.

\documentclass[a4 paper,12pt]{report}
\usepackage{graphicx}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{times}

\usepackage[english]{babel}

\usepackage[
authordate,
backend=biber,
natbib,
maxbibnames=99,
ibidtracker=false,
]{biblatex-chicago}

\addbibresource{mybib.bib}

\usepackage{csquotes}

\begin{filecontents}{mybib.bib}
@BOOK{lpd,
  title = {Longman Pronunciation Dictionary},
  publisher = {Pearson Education Limited. Essex},
  year = {2008},
  author = {Wells, J.},
  edition = {3rd},
  date-added = {2014-02-25 15:30:14 +0000},
  date-modified = {2014-04-26 18:18:22 +0000},
  keywords = {wells}
}

@BOOK{wellint,
  title = {English intonation An Introduction},
  publisher = {Cambridge University Press Cambridge},
  year = {2006},
  author = {{Wells, J.}},
  date-added = {2014-02-05 12:51:13 +0000},
  date-modified = {2014-04-25 15:24:39 +0000},
  keywords = {intonasjon}
}


@ARTICLE{wellstrans,
  author = {Wells, J.},
  title = {Transcribing Estuary English},
  journal = {Speech Hearing and Language: UCL Work in Progress},
  year = {1994},
  volume = {8},
  pages = {259-267},
  date-added = {2014-01-22 13:35:58 +0000},
  date-modified = {2014-04-26 18:18:05 +0000},
  keywords = {wells}
}

@MISC{wells1991,
  author = {Wells, J.},
  title = {The Cockneyfication of RP?},
  howpublished = {http://www.phon.ucl.ac.uk/home/estuary/cockneyf.htm},
  month = {4},
  year = {1991},
  date-added = {2014-04-12 17:01:31 +0000},
  date-modified = {2014-04-26 18:18:13 +0000},
  keywords = {wells}
}
\end{filecontents}

\begin{document}

Now, let's add some quotes from the different publications. Here is publication 1 \citep{lpd}, and number two \citep{wellint}. And then we add number three \citep{wellstrans} and four with a slightly different format, just because \citet{wells1991} probably would like it better, and try to compile it.

\printbibliography
\end{document}