Multiple Runtime Virtual Textures

Is there some kind of limit in the number of RVT’s you can setup? I have a massive landscape split into 9 tiles. I want to assign each tile their own Runtime Virtual Texture. But no matter what I try it only works for up to 7 tiles. The last two don’t write anything to their assigned RVT. I’ve rebuild the setup several times now. But no matter in which order I start to setup my tiles, the last two never work. Any ideas?