I think that's bug, thanks for reporting, tracking as https://www.ventismedia.com/mantis/view.php?id=17954

Hi,
Short Answer many devices do not support Half star ratings, if you enabled Sync back than it is understandable.

(I am OP, but it is making me type in a different username)
Sorry, after seeing the guidelines on how to report bugs let me add some information:
synced device is iPhone XR.
Most recent build as far as I can tell.
Easily reproducible (at least for me). It happens almost every time I sync the device.
Sync is over lightning cable.
I can do the stuff for syncing errors, but the sync itself is fine, it's only an issue with the library as a result of the sync.
Windows 10 OS build: 19042.985
If this is actually a bug, I'll go through the process of doing the debugview.

Whenever I sync with my iphone, the half-star ratings on my pc library are retagged to the next highest star. I understand them saving that way on the iphone, which doesn't support half-star ratings, but is it necessary to retag my library in order to sync. As a result of this all of my 4.5 star ratings are changed, and I have to retag them. In addition, all of these songs are redownloaded each time to the phone every sync. Is this a bug, or intended, in which case how do I disable it ? MMW5.