How to control the initial saturation degree in transient analysis

Hello.

I'm conducting a transient analysis to simulate the infiltration of runoff into a sump, but I'm encountering convergence issues. Despite trying all the suggestions from here, here and here ,

I continue to see red crosses in few steps (day 45-48). Upon reviewing my model, I noticed that the transition in saturation occurs too rapidly and drops to about 0.18, whereas I would expect it to be closer to 0.80. Could this be the source of the problem? With this saturation, it leads to a permeability in the order of -12, which is not what I expect from the material. Should I change the Maximum Suction from 1000 kPa to something else?

During my research, I came across the activation of the PWP (Pore Water Pressure) function within the material settings, which I'm not currently using. I suspect I might be missing something here. However, I haven't been able to fully understand this function or how to implement it. Are there any resources available on this topic? Could someone provide guidance?

Thank you!