I'm running into a bug that is also contributing to another issue with DR16 (documented in this thread:
https://forum.blackmagicdesign.com/viewtopic.php?f=21&t=101649). The bug is shown by trying to round trip FXPXML.
In a new DR project, add some clips to a timeline with several tracks (in mine I have two camera (V1/A1 and V2/A2) tracks and one additional audio track (A3). Export the XML using FCPXML (latest version). Now try to import that timeline right back into DR16 and the issues are apparent, namely, the media on a given track is not preserved on that track (e.g. I get some A3 content on A1, I also get content moved to A4 which is a new track, etc.).
This breaks Syncaila's synchronization process.