When you use lot of image in documentaion, the pdf maker crach with a "out of memory".
It is du to an option of Asciidoc "Xmx". it is seting to 1024M (very little)
Now (Java 17+) The JVM can use by design 80% of your computer memory if need (before it was 64M). Then your Xmx parameter restric memopry use, so it create a out of memory with PDF.
Solutions,
Trust in the JVM by remove this option of optimisation for serveur.
=> In the file option "AsciidocFX.vmoptions" remove -Xmx parametre.