I have a similar problem. In my case, I have a Sony DVD-RW disk. Things were fine with this disk, and I had erased and re-written around 10 times. However, the last time, I used ImgBurn to burn an ISO to this disk. The burn process went fine, and I was able to use the disk as required. However, now when I try to put new stuff on this disk, I keep getting errors. Also looked for the option to erase, but with the disk in the drive, the option for 'Drive' under the 'Tools' menu doesn't get highlighted. I am posting below screenshots of what I notice from ImgBurner.
This one is the information I get when I go into the write mode in ImgBurner.
The one below is the error I get when I try to do an erase from Mode -> Discovery.
I feel that when I burnt the image using ImgBurn, it accidentally finalized the disc. But I was under the impression that a finalized DVD-RW disc can still be re-written.
Is it possible to still write to this DVD?