getdownArchive task fails looking for the archive background image

When trying to build the getdown archive for 2.11.4.0:
gradle -PCHANNEL=RELEASE getdownArchive

fails with:
> Task :getdownArchiveDigest FAILED
Generating digest file './build/website/docroot/old/v2_11_4_0/getdown/digest.txt'...
2024/09/17 22:29:42:089 WARNING Starting without install4j classes
Exception in thread "main" java.io.IOException: Error computing digest for: resource/jalview_getdown_background.png
        at com.threerings.getdown.data.Digest$1.run(Digest.java:75)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: java.io.FileNotFoundException: ./build/website/docroot/old/v2_11_4_0/getdown/resource/jalview_getdown_background.png (No such file or directory)
        at java.base/java.io.FileInputStream.open0(Native Method)