XnConvert 1.8 - batch resize - bug?

[mustbeit]

What is wanted:
Batch reduced images height to 1080 pix, whether they are in portrait or landscape, but if their height is already 1080 or less, do nothing.


open XnConvert 1.8
1/ select an image having a height say of 1080 pix.

2/ In "Action" add "Resize" as filter, NO other active action
Select "Height" (Hauteur)
size 1080 (viz, the same height as the input image)
select "reduce only"(réduire seulement)

3/output
same folder, add _ as prefix.

4/ Execute.

Results:
Hashing input and output show different signature

Expected behaviour
output image must be identical to input, as only filter is resize and parameters exclude action.

Bug?

Thanks

P.S. At execution I get "The 'CPU Core" settings is disabled, can't be used with 'Ask' mode, or multipages, PDF files"

[xnview]

the resize is not made, but file is written in the format, not copied. So for example with jpeg, you can have a re-compress