Hello tatj89,
It sounds like you're running into an issue syncing podcasts to your iPod nano (7th generation), and we'd like to help.
"If you have an iPod classic, iPod nano, or iPod shuffle, you must sync your device with your Mac to add podcasts and other content to it." More about that here: Sync podcasts between your Mac and iPhone or iPad
For more details on syncing content from your Mac to your iPod nano, please check out this link: Overview to syncing your Mac and your devices
If the information and steps in the above links doesn't help, would you mind confirming the exact macOS version your Mac is running at this time, so we can look into this further? Find out which macOS your Mac is using
Thanks!