UrBackup Windows wrong volume

Hi all, I just started using UrBackup to backup my windows machine to my nas and I noticed that the wrong Volume gets copied.
I have two drives installed: C: (500GB) and D: (3Tb). I want to backup the system partition C:

I used the default settings in the client (backing up the system partition).
And on the client the correct volume is displayed ©.

But on the server I am seeing the wrong volume (D)

On the filesystem at the Nas there is also the wrong drive letter.
2019-08-11%2012_03_19-Termius%20-%20OMV

Do you know where this could come from?
On my windows machine the disk 0 is D: and disk 1 is C, could that be the issue?

Regards,
D3473R