I know this question is almost 2 year old, but I had to make like 30 different search to finally find the answer to your question.
I've almost abandonned Sublime because of this weird hidden setting.
Sublime just delete your tabulation as you add new lines, and this is because of this setting
You have to set in your config file :
and adding new line wont just delete your previous indentation.
I really really really dont understand the mindset of wanting to have this setting true by default, this makes less than no sense, and yes, less than 0 is possible, just look at this option