I don't know if this is intentional behavior or not, but its inconsistent, so I assume it's a bug.

If you shoot a spell charge at the -x, -y, or -z side of a block, it will stick to the bottom of the block.

If you shoot a spell charge at the +x or +z side of a block, it falls down.

Additionally, it seems that if the charge is sticking to a block, the focal point is within that block

Fixed in #571