...what, by the way, raises the question why the ubuntu installer was able to mount the USB stick, but not the USB bluray drive.
I guess this was because I had connected the USB stick to a USB 2.0 port, while the USB bluray drive needs two USB ports because of it's power consumption and therefore I had connected it to the front ports, which are USB 3.0 ports.
So maybe the reason is that the installer does not support USB 3.0 ports even when the device connected is a USB 2.0 device?
...what, by the way, raises the question why the ubuntu installer was able to mount the USB stick, but not the USB bluray drive.
I guess this was because I had connected the USB stick to a USB 2.0 port, while the USB bluray drive needs two USB ports because of it's power consumption and therefore I had connected it to the front ports, which are USB 3.0 ports.
So maybe the reason is that the installer does not support USB 3.0 ports even when the device connected is a USB 2.0 device?