I've been having recurrent problems with a soft surge line running the long side of my 4x5 negatives. The hangers are kodak (see picture), and the line occurs at the long side of the film that sits at the top, where the lever bar flips over to trap the film in the hangar. The line reflects more vigorous development - I've also enclosed a negative that illustrates it, darkened and enhanced to show the line along the left side of the film.
HP5, developed in HC110 for 5-6 mins. My agitation routine used to be fairly vigorous - raise up holders, tilt left, put back in, raise up holders, tilt right, put back in -- x4 every minute after initial agitation. But this last shot I only did it x2 per minute.
I've thought about drilling holes in the top bale, or bending it out.