cannot sync ipod nano

confutatis wrote:

When iPod connects, it shows the basic spinning wheel and says it's syncing. This lasts about two seconds and the the icon on the sidebar shows the eject symbol beside it.

Yes, I know, which is precisely why I suggested checking the Sync settings. I did not suggest that you had disabled sync, all I said was that the settings need to be checked - and with good reason.

Clicking File at the top of the sidebar, there's a Devices icon. Clicking that opens a window that shows a sync option, but it's greyed out.

No, that shows a link to "perform a Sync", not to "check the sync settings" or sync options:

To check the Sync settings, connect the iPod to your iTunes Library and click on the iPod icon when it appears:

This shows the Device/Settings/Summary pane (see below). Select Device/Settings/Music (1.) just below Summary:

• Makes sure that Sync Music (2.) is selected. I suspect that it is already
• Which option is selected in 3., is it entire music library or is it selected playlists,artists, albums and genres?
• If you have chosen selected playlists, artists, albums and genres, section 4 then appears. Have you chosen anything in section 4?

Try all the suggestions mentioned in the following links....

If iTunes doesn't recognize your iPhone, iPad, or iPod - Apple Support

Sync your iPhone, iPad, or iPod using iTunes on your computer - Apple Support

How to Fix iTunes When It’s Not Syncing with iPhone, iPad, or iPod Touch

iPod Won't Sync Music with iTunes on Windows 10 | Reasons and Solutions

Mac or Windows?

Personally, I'm not sure what you mean by a "Sync dialogue box". If you have set your iPod to Sync with your iTunes Library, no "dialogue box" will come up. Instead, from the time the iPod is seen in iTunes to the time it finishes syncing, you may (or may not) notice the messages in the top information panel, that indicate the progress of the Sync (see screenshots below). Unless you specifically click on something, you may not notice anything at all apart from the iPod icon (that is shown in the second screenshot). iTunes will not switch views, it will continue to show the the screen you were already looking at.

In this first screenshot, my iPod is connected to my computer but iTunes has yet to see it. It appears to take far too long for this simple step to be achieved and one can be forgiven for thinking that nothing is happening:

In the next screenshot, iTunes has (finally) seen the iPod, hence the iPod icon in the view, but no messages have yet been offered:

In the screenshot below, sync progress messages appear in the top window, where the Now Playing information usually appears, but below that information is the view of my Library, not the iPod:

Notice to the right of the text there are up-and-down arrows. These indicate additional messages in the window, that you can read by clicking on the arrows. However, they can change often, you may not be able to keep up with them and I wouldn't worry too much if you don't see or read them all.

In theory, when a Sync is complete you should see this in the top window:

But not always. Sometimes, iTunes may simply revert to showing information about the song it was last playing. If you are not sure whether a Sync has competed, click on the iPod icon at the top of iTunes (the one I've previously mentioned) and look for the eject icon:

The eject icon only appears once a Sync has completed. Until then, there will be two spinning arrows in its place.

Lastly, messages are specific to the sync taking place. In this combined picture of two separate syncs, notice that in the upper one, there are a total of five steps to the sync, while in the lower one, there are six.:

Now, that's all well and good, but your issue is that no Sync appears to be taking place. Perhaps your Sync options are not correct, especially if you have just performed a Restore operation using iTunes. If you require assistance to check Sync settings, please ask. (There will be more pretty pictures!)

If you have just carried out a Restore, mention this as it makes a slight difference.

That's good to know.