Hello community!

In the past few days I found out that you are able to upload or download files from the file browser via Drag & Drop. At least that was, what my friends told me. The problem I encountered is: For some reason, I can't do this.
Simply uploading and downloading files manually works.

I do have all the permissions to do so being the Server Admin of my server.

My stats are:
Windows 8 64-bit
Teamspeak v3.0.13

Did anybody already encounter and/or fix this problem?
I searched in Google for quite a while and also looked through the forums, but still I couldn't find a solution yet. Some of the solutions that were posted were pretty outdated aswell.

EDIT: My UAC is completely turned off due to the fact that it is just annoying me.