Problem with rebuilding/reloading extension changes

You must be getting errors in browser console. Which suitecrm version are you using? There is slight change as well in 8.7.1 and 8.8-beta

If there are errors related to 403, most probably the error is due to file permission (faced this a few times, after build, i had to reset permissions in /public folder because compiled files are inside public folder.

If you are facing 404 errors, probably file is not generated.

Try checking php_error logs or suitecrm logs in root folder.

There must be a hint somewhere.