Probably because the conversion/copying process is complex, ie. one track can be converting while another is being copied via USB. On very fast PCs where the file transfer is the bottleneck (mine for example with 8 processing cores), I only see "Copying..." and never see any messages for "Converting..." even though I have enabled autoconversion (FLAC -> mp3) because several tracks can be converted in the time it takes for a file transfer.

I don't really see that as a bug.

1 Run an auto-sync that converts files to WAV
2 Watch status bar

Expected: "(Converting to wav)" on every file
Observed: "(Converting to wav)" only on every second file

EDIT(TC) Tracked at http://www.ventismedia.com/mantis/view.php?id=6812