Difficult to diagnose your problem as it is hard to tell specifically how you are rinsing after development, and I have no experience with your particular fixer. Also not sure how you are washing the film during the 10 minute wash. I'm assuming Fotonal is a wetting agent.

Based on the scan it could be as simple as dust sticking to the film during drying.

Whatever the issue is, I can tell you it is not a problem with PanF+, nor is it a problem with Perceptol. It isn't related to long exposures either. Ilford films have no problem with long exposures. As you adjust exposure times for reciprocity failure, you can expose as long as you want.