No idea, I use command line too and it works fine for me:
Code:
xtool precomp -mpng+preflate -d1 Hint.png Hint.png.xtool
XTool is created by Razor12911
Version 0.8.7
Streams: 2 / 2
Time: 00:00:01 (CPU 00:00:00)
Size: 3.47 MB >> 12.3 MB
I have attached my working files below + a bat file if you want to have a go:
https://www.upload.ee/files/16621022/Test.7z.html