For a GUI job, add it here:
and get:default option value
and check it to turn it on. GUI doesn’t affect CLI, and I don’t know why your CLI option wasn’t working.
Zip-compression-zip64 clarification made me suspect Duplicati sets zip64 just-in-case, if configured.
Opening a sample tiny dlist file in 7-zip and viewing Properties of filelist.json confirms this is the case:
A different sample tiny dlist without GUI option set did not have that, so there’s one way you can test…