Posts not rendering on home page with Jekyll

I would like to help to understand why my posts do not appear on my home page from a Jekyll blog. It does not work properly local and on GitHub pages.

I have some test posts on _posts folder (i.e. 2017-11-22-a-post-about-my-research.markdown and 2014-11-28-markdown-and-html.md)

Here is a exemple of one these posts

--
layout: post
title: Feature images
feature-img: "assets/img/sample_feature_img.png"
---
This is an example of a post which includes a feature image specified in the front matter of the post. The feature image spans the full-width of the page, and is shown with the title on permalink pages.

The server starts but the posts do not are on home page.

On the other hand I can see and open the posts on tags page.

My project structure is

My gem file is like looks:

source "https://rubygems.org"

# Hello! This is where you manage which Jekyll version is used to run.
# When you want to use a different version, change it below, save the
# file and run `bundle install`. Run Jekyll with `bundle exec`, like so:
#
#     bundle exec jekyll serve
#
# This will help ensure the proper Jekyll version is running.
# Happy Jekylling!
gem "jekyll", "~> 3.6.2"

# This is the default theme for new Jekyll sites. You may change this to anything you like.
# gem "minima", "~> 2.0"
gem "jekyll-theme-type"

# If you want to use GitHub Pages, remove the "gem "jekyll"" above and
# uncomment the line below. To upgrade, run `bundle update github-pages`.
# gem "github-pages", group: :jekyll_plugins

# If you have any plugins, put them here!
group :jekyll_plugins do
  gem "jekyll-feed", "~> 0.6"
  gem "jekyll-paginate"
end

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

My conf.yml is about:

# SITE CONFIGURATION
baseurl: "/blog"
url: "localhost:4000/"

# THEME-SPECIFIC CONFIGURATION
theme_settings:
  # Meta
  title: Nielsen Rechia data scientist
  avatar: assets/img/avatar.png
  favicon: assets/favicon.ico
  gravatar: # Email MD5 hash
  description: "A website with blog posts and pages" # used by search engines

  # Header and footer text
  header_text: >
     <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.</p>

     <p>Remove all header text in <code>_config.yml</code> to disable this feature.</p>
  header_text_feature_image:
  footer_text: >
   Powered by <a href="https://jekyllrb.com/">Jekyll</a> with <a href="https://github.com/rohanchandra/type-theme">Type Theme</a>

  # Icons
  rss: false
  email_address: # Full email address, e.g. "sam@example.com"
  behance:
  bitbucket:
  dribbble:
  facebook:
  flickr:
  gitlab:
  github: "nielsenrechia"
  google_plus:
  instagram:
  linkedin:  # Full URL
  pinterest:
  reddit:
  soundcloud:
  stack_exchange:  # Full URL
  steam:
  tumblr:
  twitter: "twitter"
  wordpress:
  youtube:

  # Scripts
  google_analytics: # Tracking ID, e.g. "UA-000000-01"
  disqus_shortname:
  katex: true # Enable if using math markup
  search: True # Enable the search feature


  # Localization strings
  str_follow_on: "Follow on"
  str_rss_follow: "Follow RSS feed"
  str_email: "Email"
  str_next_post: "Next post"
  str_previous_post: "Previous post"
  str_next_page: "Next"
  str_previous_page: "Prev"
  str_continue_reading: "Continue reading"
  str_javascript_required_disqus: "Please enable JavaScript to view comments."
  str_search_no_results: "No results found."

  # Colours, typography and padding
  # Open the "_sass > base" folder, and open "_variables.scss"
  google_fonts: "Source+Sans+Pro:400,700,700italic,400italic"

  # Post navigation
  post_navigation: True

# PAGINATION
paginate: 2
paginate_path: "/blog/page:num"

# BUILD SETTINGS
publish: True
markdown: kramdown
highlighter: rouge
sass:
  sass_dir: _sass
  style: :compressed
plugins: [jekyll-paginate]
theme: jekyll-theme-type
exclude:
  - Gemfile
  - Gemfile.lock

I think it is simple, but I can't figure out what is the problem.

Thanks

The issue here is that you have an index.md and an index.html. By default, index.md gets processed into _site/index.html. Therefore, now Jekyll gets confused which index.html needs to be written to the _site directory and therefore either one gets preference.

The solution is to add any content from index.md into index.html and delete index.md