I had Tumbleweed ISO image on a USB stick and wanted to use it for Leap 15.4 ISO. So I mounted it (I have Leap 15.3 OS) to check if it was the correct USB stick. The drive did not show up either in Dolphin or in Super User mode. Suspecting that the stick had gone bad I decided to have a look at it in the Partitioner. There it showed up properly! Went back to Dolphin and still no show. Eventually I deleted the partitions on the USB stick in Partitioner. Now comes the surprising part, the drive showed up in Dolphin with the list of files of Tumbleweed ISO, but in Super User mode the drive showed clear. I did not experiment further but proceeded to write the Leap 15.4 to the drive. The image writer asked me to first unmount the disc, which I accepted, and then the image was written. When I tried to see the drive in Dolphin and then in Super User mode it was no show.
I do remember checking USB stick as well as DVDs with ISO image in earlier releases of OpenSUSE OSes. Not really sure about earlier Leap 15 versions. Is this a new feature?
When you have writen an ISO image to a device in the correct way (e.g. using dd) it does overwrite the partition tbable (if there was one). So it is quite logical no partition table is found on such a device.
When you want to write another ISO image to the device, just do it. It is complete useless and futile to first write a new partition table to it. It will be overwritten by the new ISO image as the first block is written to it.
Now the USB sticks are available in higher capacities, 16 GB and more, and the 8 Gb ones are not cost effective, I need to learn, understand and be able to use the method of writing a number of ISOs to one USB stick, or use the balance space for other purposes. Could anyone point me to a simple and clear instruction set? Thanks once again.