I actually just finished testing some other discs right after I made this post. It comes down to the brand of the media but it's a bit inconsistent. Verbatim discs are definitely working the best, in fact, they always seem to work.
The problem I reported was happening with a Maxell DVD+RW but the OS didn't have the same problem Toast was having. A few other Maxell discs did appear to register properly with Toast but I decided to toss them and go with Verbatim.
I also tested a Memorex DVD+RW. Not only did Toast have a problem with it (it froze) but my entire system had a problem with it. Choked up a bunch of apps, wouldn't eject and I had to restart.
Lesson here, folks, go with Verbatim for DVD+RWs, at least. I never have any issues with Maxell DVD-Rs.