Markdown Preview not appearing when right-clicking a .md file on macOS

Prerequisites

[x] Put an X between the brackets on this line if you have done all of the following:
- Reproduced the problem in Safe Mode: https://flight-manual.atom.io/hacking-atom/sections/debugging/#using-safe-mode
- Followed all applicable steps in the debugging guide: https://flight-manual.atom.io/hacking-atom/sections/debugging/
- Checked the FAQs on the message board for common solutions: https://discuss.atom.io/c/faq
- Checked that your issue isn't already filed: https://github.com/issues?utf8=✓&q=is%3Aissue+user%3Aatom
- Checked that there is not already an Atom package that provides the described functionality: https://atom.io/packages

Description

Markdown Preview fails to appear as an option when right-clicking a markdown file on macOS.

Steps to Reproduce

Install a fresh copy of Atom on macOS (I have 10.14.6)
Create a test markdown file test.md (see below)
Launch atom using atom .
Open the test file by clicking it
Right-click the test file

test.md contents:

# Markdown Test

Short sample

Expected behavior:

The "Markdown Preview" menu option should appear at the top, allowing you to open the markdown preview

Actual behavior:

No "Markdown Preview" option is listed

Reproduces how often:

Some files, especially small files, almost never show the right-click menu option. Larger markdown files always or almost always show the menu option.

Versions

Running macOS 10.14.6

$ atom --version
Atom    : 1.50.0
Electron: 5.0.13
Chrome  : 73.0.3683.121
Node    : 12.0.0

$ apm --version
apm  2.5.0
npm  6.14.5
node 10.20.1 x64
atom 1.50.0
python 2.7.16
git 2.28.0

Additional Information

The markdown-preview-enhanced package does not exhibit the same behavior. By default, it opens a markdown preview window that works with all .md files.

atom / markdown-preview