Default Encryption Won't Work

I've got a big problem with my new Find 7a(switched from Color OS to CM 11 from official oppo website). The full phone encryption is one of the main features that I need. My exchange server requires it.

Everything is working perfectly except the device encryption. After choosing a password, the screen shows the green android logo with a chain around the belly. I know that there should be a progress bar, but there isn't. I waited several hours and noticed that i can easily go back. The whole encryption process doesn't start, but it also throws no error message. Tried to reboot etc., nothing helped.

This worked just fine on my HTC One. I'm not sure what the problem is. I couldn't get it to work on color OS 1.2 as well as 2.0.


Thanks in Advance! I really need this feature to work.