Prettier file watcher works on all files except one specific one Follow

I posted this on SO as well, but those guys are very quick to downvote a question, so I'm posting here as well.

I created a repo that contains the code for this question, including the .idea files. There is a file watcher tasks file in there as well, though the tasks are global so I think there is probably another file specifying them. Where would this be located?

To create the repo, I simply used:

npx create-react-app ws-fw-issues

npm i -D prettier

I have some globally installed file watchers that run prettier on save; in particular, one that runs on save of simple .js files. They work on all files except for App.js, which is created by create-react-app.

I can create new files and prettier reformats them.

The prettier file watcher doesn't work for App.js however, and only this file; I can delete it and create it again, prettier won't reformat. If I rename it, then it does get reformatted by the file watcher.

I actually see "Executing Prettier JS task" at the bottom but nothing happens. Actually even though I do see this at the bottom, it appears in a different color and different location than when I see this for other files. For other files the text is white and in the middle of the bottom bar; for App.js it is blue and way to the right.

To see this in the repo, just open the project in Webstorm and open App.js. The formatting is all messed up, so change something and save; it won't reformat. Do the same thing for index.js and it will reformat on save.

I am using Webstorm 2019.3 build #WS-193.5233.80.

By the way, if I were to install typescript as a dependency and change the extension to .tsx, the TS file watcher I have does reformat that file. Why does it not reformat App.js specifically?