Why are my changes in index.html not visible after deployment?

Hi

I see that the index.html is the standard html version without my changes in the index.html file. Probably it has to do -again- with the fact that I am using Mx theme and Sass.

How can I still change index.html?

Edit 1: i tried to change the index.html file in the theme zip of the theme and rezip it again, with no results. I make use of the Silver lining theme.