Now I’m trying to make a breeze block wall with Flowify, but Flowify is making new faces in-between the blocks. What am I doing wrong?
You are doing nothing wrong, that is a bug in Flowify.
The problem is that Flowify builds up the target geometry with a PolygonMesh (a very fast internal data structure in the API). Polygon meshes do not allow inner face loops so Flowify tries to create these inner loops in a second pass but often fails.
So, in order to avoid this problem you can remove the inner face loops on the projection side. See example below. The left geometry has an inner face loop, while the geometry to the right does not. The face is split into four faces which removes the loop.
