I can see what may be happening. The developer is not flowing over the face of the print evenly as you start the agitation. I've had problems like that long ago in a different galaxy. My solution to that is to rock the tray a bit before inserting the print, making a wave go to one end of the tray. As it nears the end I slip the print down to the developer and the wave rolls back across evenly wetting the entire print very quickly. It takes a bit of practice at first but will become almost automatic very soon.