Hello GinnyandGerry.
Thank you for using Apple Support Communities. It sounds like you're experiencing issues when attempting to sync data to your iPod. If so, we'd like to look into this issue with you.
To confirm, are these specific podcasts already downloaded to your computer or are they showing cloud icons? When syncing, are you connected directly to your computer using a Lightning cable or are you syncing via Wi-Fi? If you're syncing using a Lighting cable, does testing a different cable or using a different port help?
Ever since this issue stared to occur, have you been able to restart both your Mac and iPod nano to see if you notice any change in this behavior?
Learn how to force restart your iPod
Log out, sleep, wake, restart, or shut down your Mac
If these steps don't help, you can try to test this issue in safe mode. This step prevents non-essential apps from opening up when starting up your Mac. If you're not familiar with safe mode, check out the link below:
How to use safe mode on your Mac
Feel free to keep us posted on your results.