I had all my files prepared but they were not getting compiled using SimpLESS.
There was no error being shown and yet there was no progress.
Then I remembered that we have something called less.js.
So, I went ahead and ran my files using the js. And bingo, errors came up which earlier didn't show.
Somehow, CSS3 Filter Properties were not being rendered because of their mixin like nature.
sepia and the others, they all failed the test.
I removed them and it was getting compiled.
There are still some problems with the SimpLESS compiler but it's good enough to use on Windows.