Do you fill the tank in the normal way through the daylight cap? That could be an issue. Try filling the tank in the dark and then immersing the reel(s) in it before putting the cap on and turning on the lights. I do this with my Nikor 4x5" tank with PMK, since it's pretty slow filling. I think it's okay to proceed with the lights on after the initial fill, since the developer is pretty spent by the time you're ready to dump it.

A presoak might be another thought.