This has come up occassionally in our office, where the PDF option becomes unavailable. We simply re-install the PDF Converter (Program Files\Graphisoft\ArchiCAD 10\PDF Converter\Install) on that machine and all is well. I'm not sure if this is the best way to remedy the problem, but it works for us without incident. Did you try to re-install the PDF Converter after following the steps in the attached link?
MacBook Pro Apple M2 Max, 96 GB of RAM
AC26 US (5002) on Mac OS Ventura 13.5