@ksmets I use a similar approach with apache and do not have any problems. Can you try using the web console in Firefox or something similar in a different browser to see the network requests and responses. That might shed some light on what is happening.
Looking at both de browser console and debug logs. I see that php-fpm returns “Status: 500 Internal Server Error”. I tried restarting/reloading php-fpm but can’t get the symbolic link to work.
Resolved the issue. Apparently restart of php5-fpm didn’t kill the pool processes. Manually killing all php5-fpm processes and restarting php5-fpm did the trick.