http://www.lyx.org/trac/ticket/6712
lyx2lyx is definitively not the reason. I use the same iconv.dll for all LyX versions, so iconv is also no guilty. However, I compiled LyX 1.6.6 against Qt 4.5.3 and LyX 2 against Qt 4.6.2.
Is this bug also reproducible on Mac and Linux? regards Uwe