Apple USB Superdrive doesn't read DVD-RW video disks

I've just got a new iMac (Retina 4K, 21.5-inch, 2019) which is running OS 10.14.5 along with an external Apple USB Superdrive.

I have a large collection of videos on DVD, some purchased but some recorded on a Toshiba RDXV59DTKB video player/recorder.

I can play commercial DVD recordings from the Apple USB Superdrive and DVD-R and DVD+R disks I recorded myself.

However, when I load a DVD-RW, no files or folders show in the Finder and no applications will play the disk. And yes, they have been finalised.

There are videos on these disks - I can load the disk in to the Toshiba and play the video. I can also dub the videos back to the Toshiba HDD and then re-record them back to a DVD-R and play that in the Superdrive. So, I can still get at the videos on the iMac with the Superdrive but it is a hassle dubbing back the the HDD and then re-recording onto a DVD-R.

Suggestions please to getting the DVD-RW disks working in the Superdrive?