All my star ratings are gone!

2 things are important here:

iTunes rating system is NOT the same as the Rekordbox rating system they need a translation in order to work. iTunes ratings are written back to the track's metadata (in a iTunes proprietary tag). I'm not sure if Rekordbox's tags are contained in the database only or written back to the tracks.

Now for the good news:

Rekordbox 5 got a great new feature, import the playlists, cues and loops back from a USB into the collection. I show it in action at 

https://www.youtube.com/watch?v=8uSF2Ox0yMk&feature=youtu.be

time index 1:55, including the tiny bug it contains, but in general it works great and most likely will safe your day to :)

I'm excited to see if your solution works, but unfortunately the link you provided is taking me to my own channel's Video Manager screen.

I also want to clarify again that my library is now in three places: rekordbox, my original USB, and my new, secondary USB. The star ratings are not present on any of them anymore (the star ratings were still on my original USB until I tried to use the sync utility to get the star ratings back into the library on my computer, but they disappeared instead).

I hope that doesn't change anything.

my bad, link is updated in the original reply.

let's hope it has not sync'd them blank because in theory your backup drive's modification dates will be "later" then the original tracks, hence marking them candidate to be the source rather then the target for the sync manager.

try what I show you in the video

Great news: I just found out that my star ratings are still present on the secondary USB.

Because of this, I am approaching every step with caution, because I'm terrified of losing them.

A few questions: If I simply copy/paste the "Pioneer" and "Contents" folders straight off of the USB, as a temporary backup, will that retain the star ratings?

Secondly, if I do this playlist trick as shown in the video, will the star ratings carry over to the Collection, or just the imported playlists?

Thanks so much, you're a real hero.

wow that's great news indeed! 

I'm a Mac guy, so I would use a tool like carbon copy cloner to make an exact duplicate of the original disk. This includes owernship and modification dates of the track files.

the Imported Playlists ARE part of you collection.only the tracks they contain may or may not be on your harddisk or a USB, depending on the import settings you used.

For the Pioneer specific questions, maybe some of the mods can help in that department.

thnx for the compliment and more then welcome

UPDATE:

I tried the Import Folder trick outlined in your video and nothing happened. My collection still has blank star ratings, and my USB still has them filled up.

Yeah, I could use a mod right about now. Thanks anyways!

Why not connect the export USB stick, right-click on it and select "Update Collection"? That should bring all the content back from the stick to update the collection data.

Sounds like you didn't quite understand how the "sync manager" worked and thus overwrote the data on the first USB drive with the blank data from the collection.

iTunes and rekordbox have a funny relationship. Personally, I never use iTunes for the fact it can make a mess of everything so elegantly.