Using collection tag filter to exclude a certain tag doesn't work on index page

[HahnJustin]

I just modified my routes.yaml to look something like this:

routes:
  /portfolio/art/:
    controller: channel
    filter: tag:portfolio+tag:art
  /portfolio/figure-drawing/:
    controller: channel
    filter: tag:portfolio+tag:figure-drawing
  /portfolio/pixel-art/:
    controller: channel
    filter: tag:portfolio+tag:pixel-art

collections:
  /portfolio/:
    permalink: /portfolio/{slug}/
    filter: primary_tag:portfolio
    template: tag
    data: tag.portfolio

  /:
    permalink: /{slug}/
    template: index
    filter: tag:-portfolio

taxonomies:
  tag: /tag/{slug}/
  author: /author/{slug}/

But somehow the portfolio tagged posts still show up on the home page. Though interestingly the issue does not occur when using the Casper theme.

[augusto-romero-arango]

Take a look to: https://github.com/TryGhost/Source/issues/33