@DavidCarlisle I just looked at this question https://tex.stackexchange.com/questions/653677/using-both-packages-ltxgrid-and-pdfpages-together-rotates-body-text-90-degrees. It breaks because it loads lscape, and the ltxgrid package then patches the output. The comment in the docu "For compatibility with David Carlisle's lscape package, we need to allow the
\LS@rot procedure to mung \@outputbox. the lscape package effectively tailpatches two LATEX internals to accomplish its purpose, an approach that is not robust. It is more robust to headpatch \@outputpage, which is what we do here."