Lossless JPEG batch rotation

[Ezhe]

Hi all!
I'm using XnViewMP 0.79 and trying to rotate .JPG pictures basing on EXIF data.
When I choose Batch convert and Rotate action with EXIF orientation activated, I get lossy conversion as a result. Filesize reduces twice.
Output format is set "as original" and no conversions are activated.
And when I use manual function "Rotate based on EXIF orientation field" everything goes right.
What I"m doing wrong? How to get batch lossless rotation?

Thanks in advance.

[xnview]

Tools>Transformation>Lossless rotation