GhostText: Default syntax "***" is not installed!

1. Summary

I don’t understand, how I can set syntax for GhostText tabs.

2. Expected behavior

Writing messages in syntax, which I set. No errors in Sublime Text console.

3. Actual behavior

In Sublime Text console:

Default syntax "MarkdownEditing/Markdown" is not installed!

4. Settings

I use MarkdownEditing, AcademicMarkdown and ApplySyntax packages.

My User/GhostText.sublime-settings file:

{
    "default_syntax": "MarkdownEditing/Markdown",
    "new_window_on_connect": true
}

Part of my User/ApplySyntax.sublime-settings file:

"new_file_syntax": "MarkdownEditing/Markdown",

It means that I open my new files in MarkdownEditing/Markdown syntax of MarkdownEditing package.

5. Steps to reproduce

I reproduce the problem in a version of Sublime Text without plugins and user settings.

1. I open any page in my browser → I click to «Ghost» button in Firefox → I select textarea field → connection establish → in GhostText tab of Sublime Text I open Sublime Text console and I see in it:

Default syntax "MarkdownEditing/Markdown" is not installed!

I input in Sublime Text console:

>>> view.settings().get('syntax')
'Packages/MarkdownEditing/Markdown.tmLanguage'

1. I delete "default_syntax": "MarkdownEditing/Markdown", line into my User/GhostText.sublime-settings file → I open any page in my browser → I click to «Ghost» button → I select textarea field → connection establish → in GhostText tab of Sublime Text I open Sublime Text console and input in it:

>>> view.settings().get('syntax')
'Packages/AcademicMarkdown/AcademicMarkdown.tmLanguage'

Syntax incorrect for me, I want Packages/MarkdownEditing/Markdown.tmLanguage syntax.

1. I input in User/GhostText.sublime-settings file Packages/MarkdownEditing/Markdown.tmLanguage, MarkdownEditing/Markdown.tmLanguage, Packages/MarkdownEditing/Markdown instead of MarkdownEditing/Markdown → I get behavior, for example:

Default syntax "Packages/MarkdownEditing/Markdown" is not installed!

>>> view.settings().get('syntax')
'Packages/AcademicMarkdown/AcademicMarkdown.tmLanguage'

If I set MarkdownEditing/Markdown in User/GhostText.sublime-settings file, I get expected syntax for new GhostText tabs, but I get Default syntax "MarkdownEditing/Markdown" is not installed! in console.

6. Environment

Operating system and version: Windows 10 Enterprise LTSB 64-bit EN Sublime Text: Build 3126 Firefox: 51.0.1 (64-bit) GhostText for Firefox: 1.2.4.1 GhostText for Sublime Text: 1.0.13

Thanks.