Missing number error with LuaLaTeX and standalone under LaTeX 2020/10/01

Question

I have troubles using TikZ externalize and standalone. It seems that the required PDF is not generated. First, I suspected the recent PFG update (https://github.com/pgf-tikz/pgf/issues/932) but after some tests it seems to be related to standalone.

In my MWE I have four files.

file2:

% !TeX TXS-program:compile = txs:///lualatex/[--shell-escape]
\documentclass[class=report,11pt,a4paper,tikz,]{standalone}
\begin{document}
    \begin{tikzpicture}
    \draw (0,0) -- (1,1);
    \end{tikzpicture}%
\end{document}

file1:

% !TeX TXS-program:compile = txs:///lualatex/[--shell-escape]
\documentclass[]{report}
\usepackage{tikz}
\usepackage{shellesc}
\usetikzlibrary{external}
\tikzexternalize[prefix=tikzfiles/]
\usepackage{standalone}
\begin{document}
\input{file2.tex}
\end{document}

File3:

\begin{tikzpicture}
\draw (0,0) -- (1,1);
\end{tikzpicture}%

File0:

% !TeX TXS-program:compile = txs:///lualatex/[--shell-escape]
\documentclass[]{report}
\usepackage{tikz}
\usepackage{standalone}
\begin{document}
\input{file2.tex}
\end{document}

File2 works while file1 results in errors:

Output from main log:

 ! Package tikz Error: Sorry, the system call 'lualatex -shell-escape
 -halt-on-e rror -interaction=batchmode -jobname "tikzfiles/file1-figure0" "\def\tikzextern
 alrealjob{file1}\input{file1}"' did NOT result in a usable output file
 'tikzfil es/file1-figure0' (expected one of .pdf:.jpg:.jpeg:.png:).
 Please verify that y ou have enabled system calls. For pdflatex, this
 is 'pdflatex -shell-escape'. S ometimes it is also named 'write 18' or
 something like that. Or maybe the comma nd simply failed? Error
 messages can be found in 'tikzfiles/file1-figure0.log'.  If you
 continue now, I'll try to typeset the picture.

Output from the log in the tikzfiles folder:

\providecommand \oddpage@label [2]{} ] 
! Missing number, treated as
zero. <to be read again> 
= l.11 \end{document}

However, calling file3 from file1 works, so the problem does not seem to be related to externalize (alone).

file0 on the other hand errors without using externalize so I suspect standalone.

And the log:

(./file2.tex ! Missing number, treated as zero. <to be read again>  = l.11 \end{document}