zip backups failing

There are reports of backups in zip format (the default?) failing:

https://www.howtoforge.com/community/threads/i-get-some-errors-after-upgrading-to-ispconfig-3-2.85384/page-4#post-413058

https://www.howtoforge.com/community/threads/i-get-some-errors-after-upgrading-to-ispconfig-3-2.85384/page-5#post-413569

I'd suspect the directory exclusion syntax is bad, or possibly only happens when jailkit chroot directories exist and are automatically added to the list.