Hi,
I've just found out, when I use "Media > Add new" and Upload a PNG, it directly creates the issue. As "Convert PNG to JPG" is on, it seems like it douse this directly after upload and directly fails to write the new GUID (and rest) to the Database. To me, easy to reproduce and at least at my environment, an unavoidable bug. ;( I have to turn of PNG to JPG, to get it work just right.
Could you reproduce this issue, too?
Greez WrYBiT