Small caps don't work

[bobismijnnaam]

Description

Small caps words with \textsc stay normal. It seems that the font is missing or it's not set up. How can I restore the regular small caps font?

Minimal Working Example

\documentclass{kaobook}

\begin{document}

ABC \textsc{abc} abc

\end{document}

Expected behavior:

Actual behavior:

Additional Information

I'm on TeX Live 2019, so it might also be a problem with my distro being outdated... Unfortunately that's difficult for me to test at the moment, but I'd be okay with if that was the way to fix it ("just update").

[bobismijnnaam]

Currently I'm using the following workaround to selectively enable Latin Modern (I think):

\makeatletter
\let\scshape\relax % to avoid a warning
\AtBeginDocument{
  \DeclareRobustCommand\scshape{%
    \not@math@alphabet\scshape\relax
    \ifnum\pdf@strcmp{\f@family}{\familydefault}=\z@
      \fontfamily{lmr}%
    \fi
    \fontshape\scdefault\selectfont}
}
\makeatother

Just put this somewhere before \begin{document}. Courtesy of https://tex.stackexchange.com/a/193411/193023 and https://tex.stackexchange.com/a/193411/193023.