The German website, heise online, has reported that Maxell will not be selling their 12x DVD-RAM media in Europe due to incompatibilities with Toshiba drives. Instead, it will be sold exclusively in Japan. Here's part of their article, translated from German:
No 12X-DVD-RAM-Medien for Europe Maxell, one of the most important medium manufacturers for DVD-RAM, will not sell DVD RAM media, which can be described and read with 12X or 16X in Europe. As reason Maxell indicated serious compatibility problems among other things as Toshiba drive assemblies. The high-speed media (DVD-RAM2 called) are incompatible generally to the past DVD-RAM, which is specified to 5X. In older drive assemblies the Discs is not recognized not only, they could put also the entire computer lamely and in exceptional cases even the hardware damage.
Maxell estimates the problem as extremely serious, it has however nothing with the quality of the media to do. Since the European market for DVD-RAM is very small eh, one will sell the fast DVD-RAM2-Discs exclusively in Japan.
I can't see Maxell selling their 12x DVD-RAM media in the US either as the demand is even smaller than in Europe. If you'd like to read more, the entire article can be found here.