A little update:
I found out that I have to activate Hostdev Passthrough (is this really necessary for USB devices?). Now I see all the devices and I can add also an USB device.
But I'm still not able to disconnect the USB from the old VM.



---------- Forwarded message ----------
From: Jon bae <jonbae77@gmail.com>
Date: 2018-02-12 16:14 GMT+01:00
Subject: Can't add/remove usb device to VM
To: users <users@ovirt.org>


Hello,
I run oVirt 4.2.1, in 4.1 I added a USB device to a VM and now I wanted to change this device to a different VM.
But I found out, that I'm not able to remove this device nor I'm able to add any device to any VM. The device list is empty.

I found a bug report, what describe this error:
https://bugzilla.redhat.com/show_bug.cgi?id=1531847

Is there a solution for that?

The USB device is a hardware dongle and it is very impotent for us to change this.

Any workaround is welcome!

Regards

Jonathan