Audio books ripped from CDs and Catalina

I have several audio books that I have ripped from CDs. This was done in iTunes and once ripped you tell iTunes that the selected files are audio books. They then turn up in Books. So far so good. I have installed Catalina. I can see the audio books in Books. I want to synch them to my iPod Touch. They show up in the Finder window when I connect my iPod to my Mac. When I sync they don’t arrive on my iPod. Any suggestions please?