Apparently after an upgrade of either Outlook and/or SpamSieve when having selected a mail and training SpamSieve, it does not work anymore (i.e. it doesn’t move the mail to junk for example), used to work fine for a very long time.
I am referring to this functionality:
To train SpamSieve with spam messages, select one or more of them and then choose SpamSieve - Train as Spam from the Script menu.
To train SpamSieve with good messages, select one or more of them and then choose SpamSieve - Train as Good from the Script menu.
The versions of macOS, Outlook, and SpamSieve that you have are compatible. Updating SpamSieve does not change the Outlook scripts that you’ve installed, but perhaps your copies are damaged. You could try choosing Install Outlook Scripts from the SpamSieve menu.
You can also use the Open Log command to see which messages have been trained. It may be that the messages are being trained with SpamSieve but that for some reason Outlook isn’t moving them.