So, I usually get a notification when there's an update for PShop. This time AFAIK this didn't happen. When I launched PShop from the dock it launched what I thought was the latest version - but it actually wasn't and the neural filters didn't work. So I phoned Adobe support and they told me that there was in fact a newer version. Did a search in my applications folder and found the newer version - that I wasn't aware had been installed. Dragged its icon to the dock and launched it and presto everything now works.