Incompatibility between cdmath=false and siunitx in math mode

[aegeeik]

Using tudscrreprt with the option cdmath=false yields some weird behaviour when using siunitx to fontset numbers, it uses the wrong font. Normally siunitx' option detect-all helps to overcome this problem, but with tudscr this does not work for typesetting inside math mode. (Edit: Skip to the the update in the first comment from here on) Only an additional \sisetup{math-sf=\mathrm} can help. I believe this is a bug in tudscr or a weird set font option making it break siunitx.

Here is my MWE:

\documentclass[cdmath=false]{tudscrreprt}
\usepackage[		
		detect-all=true,	%für richtigen Font im Fließtext und Voraussetzung für den richtigen Font im Mathemodus
		]
		{siunitx}
\sisetup{math-sf=\mathrm}	%für richtigen Font im Mathemodus; bei Übergeben dieser Option direkt beim Laden des Pakets hängt sich mein pdflatex auf

\begin{document}
	12340 Text

	\num{12340} Text-Num

	\(\alpha = 12340\) Math

	\(\alpha = \num{12340}\) Math-Num

\end{document}

[aegeeik]

Update:
The problem seems to be a difference in the way tudscr sets the fonts when defined inside the preamble or after begin{document}. Loading the cd fonts inside the preamble creates the problem, loading them later doesn't create it.

See the updated MWE:

\documentclass[cdfont=false]{tudscrreprt}
  %\TUDoptions{cdfont=true, cdmath=false}	%problematic
  \usepackage[detect-all=true]{siunitx}
  %\TUDoptions{cdfont=true, cdmath=false}	%also problematic
\begin{document}
  \TUDoptions{cdfont=true, cdmath=false}	%okay
  12340 + \num{12340} + \(12340 + \num{12340}\) (First couple and last couple should look the same)
\end{document}

[mrpiggi]

Using siunitx together with 100 entries or more via biblatex gives some undesired formatting

\documentclass{tudscrreprt}
\listfiles

\usepackage[ngerman,KeepShorthandsActive]{babel}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}

\usepackage{siunitx}

\usepackage[backend=biber,bibstyle=numeric]{biblatex}
\addbibresource{test.bib}


\begin{document}

\nocite{*}
\printbibliography

\end{document}

MWE.zip
Workaround

\ifcsundef{tud@[email protected]}{%
  \AfterPreamble{\addtolength{\labelnumberwidth}{.75ex}}%
}{%
  \csuse{@latex@warning}{Enlarging \string\labelnumberwidth\space unnecessary!}%
}