Let's try this script below:
DirectShowSource("test.mkv", fps=25, ConvertFPS=true)
Crop(124,110,-132,-114) # cuts some unnessary area, such as hard subtitles, letterbox, etc.
LanczosResize(560,256) # resize the video
AddBorders(60, 0, 60, 0) # <--- this line, when it is after LanczosResize(), causes the video failed, because TOP and BOTTOM are both ZEROs
# if it changes to this :
AddBorders(60, 0, 60, 2) # <--- this line works, seems it's because TOP and BOTTOM are NOT both ZEROs
and, this bug still remains in AviSynth v2.6 alpha series by my testing.