SpamSieve doesn't quit with Mail (macOS 10.12)

SpamSieve doesn’t quit with Mail (macOS 10.12), not in the previous 2.9.34 beta and nor in the current 2.9.35b1, even as this preferences have been checked. otherwise SpamSieve seems to be fully working. I tried unchecking, quitting and checking again, but this doesn’t help

Are there any other mail programs that are still open when you quit Mail?

No, I don’t have any other Mail applications.

Please click this link to enable some debug logging. Then, when you quit Mail and SpamSieve fails to quit, please save a diagnostic report.

Thank you. I’ll do this if the problem resurfaces, but for now it went away just like that after the latest 2018-006 security update.