sub is_file_newer, lines 318..

    foreach ( sort keys %{$test_hash_ref} ) {
        my $path = $test_hash_ref->{$_};
        $path .= "/" if "$path" ne "";
        $path .= "$_";
        print_message("checking '$path' ...") if $extra_verbose;
        my $mtime = (stat($path))[9];
        return 1 if $reference_stamp < $mtime;
    }


I think correcting the following minor typo should solve it:

$path .= "$_";
->
$path .= $_;

i don't think so. the line mentioned is no typo but the atempt to quote whatever
filename may be in "$_".

the actual issue is that the filedates are checked but not if a specific file
was already taken into account at last run. imaginge a incomplete "d.lst" which
fails to deliver a specific "*.res" file (and the according "*.ilst"). if this
"d.lst" is fixed some day but the "*.res" is not recreated, the now delivered
"*.ilst" file will not trigger packing the images. the "*.ilst" is older than
the "images.zip".

one possible fix could be to protocol the "*.ilst" file used to create the
archive last time. if there exist files not in this list (or the other way
round) repacking must be triggered regardless of timestamps.