I tested Agfa-Gevaert Aviphot Pan 80, 200 and 400.
If you look at the film support you will see it has a greenish filing.
These particles on the support, when process in Kodak D 96 developer, go to the developer and eventually go on the emulsion from where they could no longer be removed.
It was something like the graphite left after the ECN 2 color process.
When I use isopropyl alcohol in the developer I do not have these defects anymore.
Before, I tried with the prebath before the developer, but the black spots still appeared on the films.
Here you can see Agfa-Gevaert Aviphot Pan 80, 200 and 400 tests in developer with Isopropyl Alcohol and developer without Isopropyl Alcohol :
https://www.flickr.com/photos/21121448@N06/37505314164/
https://www.flickr.com/photos/21121448@N06/5713454489/
When I used isopropyl alcohol in the developer I did not have to use photo flo.
The films were so clean.
I do not know if you have the same problems?
George