OC can't write to folder but www-data can

Edit: Nvm, I apparently just had to reboot the whole system and now suddenly it works...

Hi everyone,

I recently completely fucked up my Raspberry Pi and decided it would be way less effort to simply start from scratch again. I had my owncloud files on an external hard drive mounted with ntfs. I'm now at the Point where I have to configure owncloud via the browser page and try to to set a folder on my external drive (/media/bipra/owncloud data) as data folder again. However, I get the error:

Can't create or write into the data directory /media/bipra/owncloud_data

But afaik owncloud uses the www-data user to write stuff, right? So I tried

sudo -u www-data touch /media/bipra/owncloud_data/test.txt

which works fine. Also,

sudo -u www-data ls -l /media/bipra/


-rwxrwx--- 1 www-data www-data 38 Feb 7 2015 itsmounted.txt
drwxrwx--- 1 www-data www-data 4096 Jul 2 21:11 owncloud_data
drwxrwx--- 1 www-data www-data 0 Feb 9 2015 System Volume Information

I'm mounting the drive on startup via the fstab file:

/dev/sda1 /media/bipra ntfs-3g defaults,umask=0007,uid=33,gid=33 0 0

For reference: I'm using owncloud 10.0.2 on nginx 1.6.2 on a Raspbian Jessie.

I'm quite confused as to what the Problem here could be. Any ideas?