Thanks for the scene file. Something appears to be amiss here, I suspect a bug so we're going to have to take a closer look and get back to you. In the meantime, you may be able to get around it by using a compose operator instead of a Sequence (although adaptive mode still appears to cause issues).
One way to avoid this completely by using the Start, End, Corner and X Evenly inputs to create the pattern instead of using sequence operators for the X axis. This would probably be my preferred approach anyway.
Apologies for the inconvenience, I'll let you know once we have learned more.