loves rating removed when sync iPod Nano

Yes, it happens... The Love field was added when the Apple Music subscription streaming service started. The old onboard software of iPods (except for recent iPod touch models supported by Apple Music) does not know about the new Love field for songs, and I think that causes this problem.

If you don't subscribe to Apple Music, you may want to use the Song Rating (one to five stars) field instead. You can rate a song while playing it on your iPod. You can't love a song on your iPod. If you use automatic syncing between iPod and iTunes library, song ratings made (or changed) on iPod sync back to iTunes library.

If you do subscribe to Apple Music (like I do), the Love field is there to communicate your musical taste to the service. I equate 5-star rating to Love. So, every loved song also has 5 stars. I have a smart playlist that shows me all songs in my library with a 5-star rating that do not also have a Love. It's rules and settings look like this

Periodically, I check this smart playlist. If I see any songs there, I Select All in the playlist, right-click selection, and Love.

This happens with my 80GB Classic, too. It also seems to happen at random; wiped out my "loveds" the first time I synced it (it's been at least 3 weeks since the last time), but not on subsequent attempts... until some unknown amount of time goes by.

Awesome! Thanks for the reply... one less mystery to solve 😉