I’m finding issues flowing from a periodic base to a flat target. This is the clearest issue. Here, the normal of these blocks’ definition matches the base surface’s normal.
This is related, but different. These are a group flown rigid instead of a block. It also is happening from a flat base to a periodic target. The parent group is centered in the X and Y, but on the target, the orientation does not match the target’s surface normal.
Hello - it looks to me like the culprit is the line - if that is included in the group the thing skews but if it is left out, or if another one is added on the other side, the flow stays balanced. A point off to one side also messes it up.