Headings not formatting any differently than without the plugin
I'm not sure if I'm expecting too much or misinterpreting the screenshots, but when I use headers with the plugin installed I don't get any visual heading colouring changes, apart from the hash symbols themselves changing colour. I thought that the whole heading line would change colour.
Because of this the plugin doesn't seem to do anything when working on markdown files and the experience is the same as without the plugin.
The primary purpose of this package, next to providing backports of latest Markdown syntax for older ST releases, is providing various input helpers to simplify or improve writing experience.
It's Markdown syntax is an extended version of ST's default Markdown, primarily adding syntax highlighting for many 3rd-party languages in fenced codeblocks.
In order to support those extensions in all Markdown dialects, such as Markdown (Go) or any other template language, MarkdownEditing overides ST's default Markdown.sublime-package. So even if you seem to use ST's default Markdown syntax, it is actually MarkdownEditing's one - anywhere.
Fixes are actually added to MarkdownEditing first, and than ported to ST's default Markdown syntax.
By nature syntax definitions just assign scope names to tokens. Color schemes are responsible to pick up those scope names and assign colors. MarkdownEditing provides some color schemes, said to be optimized for prose writing, but just for historical reasons. They are not actively maintained.
As long as ST's status bar displays any sort of Markdown or Markdown (Go) syntax being used, MarkdownEtiting's input helpers should be functional.
If not, make sure not to have any of those legacy heavily outdated Markdown syntax packages installed, such as Markdown Extended etc.