I am periodically getting characteristic light streaks on photos like the one below.

Click image for larger version.  Name: 201908-08-02.jpg  Views: 42  Size: 115.7 KB  ID: 194561

In this instance, the streaks are most visible on the trees, particularly the left one.

The puzzle: this is one of six images from the same set exposed in a GRAFMATIC back. The other five do not show these streaks. This was the second image exposed in the back on the same day. I have had this happen several times: the same, characteristic streaks from only one image from the same Grafmatic.

The camera is a Polaroid 900 converted to 4X5 by Alpenhaus. The lens is an older 150mm Fuji 5.6 (inside lettering).

My theory to date is that this is lens flare due to poor coating or some other issue, although I do use a lens hood. The only commonality in the affected images that I can see is a source of brightness in the scene: in this instance the large white building. But I really have no idea and would welcome opinions. Should I be looking at the septums (or maybe that is "septa")?

Ah yes, the developing: All films in the same MOD 54 insert, Paterson system tank, which I have been using without issues for a while. HC100/B, although I can't see why that matters.

Thanks for any ideas.