Hello iPodShuffleMonterrey,
Let's take a step back for just a moment. Are you seeing the iPod shuffle listed in Finder when connected to your Mac? Since the last time you were able to sync your devices, has anything changed regarding software? Do you have an alternate cable you can use to connect your iPod to Mac? If so, would you give that a try and see if it helps?
If you haven't done so yet, try restarting both devices to see if that helps.
How to force restart your iPod shuffle - If you're unable to restart it with the power switch, you can use the directions provided in this article.
Best regards.