Ember CLI + Watchman Not Detecting Addon Changes

I have an Ember.js addon which Watchman does not seem to operate correctly with. Any changes made to the addon-name/app files do not trigger a rebuild. However, changes to files within addon-name/tests do trigger a rebuild.

I have a .watchmanconfig file set up as follows...

{
  "ignore_dirs": [ "tmp", "dist", ".idea", "docs", ".git", "node_modules" ]
}

After running the dummy app with ember s, I checked watchman watch-list and do not see the addon listed in the "roots" category. I've added it manually, but that does not help either, as I'm guessing ember s has to tell watchman what to do when the files are changed.

Any ideas on what might be happening?

OS: Mac OSX High Sierra (10.13.4)
Ember: v3.1.0
Node: v8.11.1
NPM: 6.0.0
Yarn: 1.5.1