I decided, for fun, to make a version (idk, as it should be called) based on the TerraFirmaGreg modpack. But when I try to import an area from the world, it just doesn't work, only lava, ordinary water, flowers, and bedrock are displayed.
Is there really some kind of internal block id filter in m-i itself, or something like that? The author of the Continuation Build somehow adds blocks from new versions...