beamermiktexsiunitx
As said in the title, I started having this problem that I didn't encounter before. After some trial and error, I discovered that siunitx is the problem (It doesn't give problems when using the article class).
I use MiKTeX with TeXstudio in Windows 10.
Here is a minimal working example:
\documentclass{beamer}
\usepackage{siunitx}
\begin{document}
\begin{frame}
some text
\end{frame}
\end{document}
This problem does not occur with TeX Live 2020 (tested on Overleaf).
I am definitely unfamiliar with both beamer and tikz (do not quite get what the \only are supposed to do) but perhaps this could go in the direction you want:
\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{chains}
\newcounter{count}
% helper macro:
\long\def\GobToSemiColon #1;{}
\newcommand\myPicture{
\begin{tikzpicture}
\begin{scope}[start chain = going below]
\ifnum\value{count}<1 \expandafter\GobToSemiColon\fi
\ifnum\value{count}>3 \expandafter\GobToSemiColon\fi
\node[draw, rectangle, on chain] {display only when counter is between
1 and 3};
\ifnum\value{count}>-1 \expandafter\GobToSemiColon\fi
\node[draw, rectangle, on chain] {display only when counter is
negative};
\ifnum\value{count}<100 \expandafter\GobToSemiColon\fi
\ifnum\value{count}>200 \expandafter\GobToSemiColon\fi
\node[draw, rectangle, on chain] {display only if counter is between
100 and 200};
\ifnum\value{count}<3 \expandafter\GobToSemiColon\fi
\ifnum\value{count}>20 \expandafter\GobToSemiColon\fi
\node[draw, circle, on chain] {only when counter is in the range 3 to 20};
\end{scope}
\end{tikzpicture}
}
\begin{document}
\begin{frame}
\only{\setcounter{count}{-3}\myPicture}
\only{\setcounter{count}{105}\myPicture}
\only{\setcounter{count}{39}\myPicture}
\only{\setcounter{count}{2}\myPicture}
\only{\setcounter{count}{5}\myPicture}
\end{frame}
\end{document}
You do need to tell beamer what you want to appear in each frame of the handout version. You can use \onslide specifications to do this so that you do not need to modify the existing overlay specifications at all. (I'm not sure this is what you want - probably not.)
The following code modifies your MWE so that, in presentation mode, there would actually be 10 slides within the frame. These are then placed on slides 1 or 2 of the handout. This is a waste of code: if you only want to show slide 5 and slide 10, you do not need two \againframe but only one. But, anyway, with the two:
\documentclass[handout]{beamer}
\begin{document}
\begin{frame}<1-| handout:0>[label=foo]{My only frame}
\begin{enumerate}[<+->]% or whatever you like for presentation mode
\onslide<1-| handout:1-2>
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\onslide<1-| handout:2>
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\end{enumerate}
\end{frame}
\againframe<0| handout:1>{foo}
\againframe<0| handout:2>{foo}
\end{document}
More efficiently with only one repeat:
\documentclass[handout]{beamer}
\begin{document}
\begin{frame}<1-| handout:1>[label=foo]{My only frame}
\begin{enumerate}[<+->]% or whatever you like for presentation mode
\onslide<1-| handout:1-2>
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\onslide<1-| handout:2>
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\item Item \arabic{enumi}
\end{enumerate}
\end{frame}
\againframe<0| handout:2>{foo}
\end{document}
I'm not sure how this could apply to article mode since then there are no frames or slides.
Best Answer
I've located the issue and there will be an update to CTAN shortly. It's a simple error - I've accidentally grabbed an argument that's eating up a test.