After a month, Panasonic released an updated version of the firmware.

http://panasonic.jp/support/global/cs/dsc/download/LX3/index.html

Improvement this time:

  1. Improved white balance flash mode setting when DMW-FL220 is connected.
  2. Proper setting of shutter speed on iA mode and Scene mode when OIS is turned ON.
  3. Proper Exif information in the JPEG picture file.

Gonna test it tomorrow :)