Browsersync/Browser Refresh not working on localhost with multilanguage setup

Has anyone experienced problems with browsersync/browser refresh on a localhost multilanguage setup?
It worked with the built-in PHP server, but I had to switch to MAMP due to this issue

The sync/refresh works fine for the panel, only the rendering of templates is not working.
And I gues it is related to the language routing. I tried setting 'url' => '/'on the default language setting, but no effect here.

I am using Codekit as a browser sync tool.

UPDATE:
Browser sync works again after I added SCSS files, compile them and include them in my header snippet. Strange…