Your comments

Thanks Forrest - yes I did find it suddenly started working though I couldn't latch it to any particular update. Helpful to understand the whitespace exception - cheers 

I'm using 

sublime-text-haml-sass but have no comment toggling - which is more of handicap than one might first think. Does anyone know if  the comment toggling controlled by the syntax - or should I look elsewhere for a solution?

Absolutely please - this really is an OS wide basic - quite frustrating to find it's missing - this is the first editor I've used without drag opt copy/clone