Instability Issue During Infiltration Step in Anura3D Landslide Model

[Aidamehr]

Dear Anura3D Community,

I am facing an issue with a landslide model in Anura3D, and I would be deeply grateful for any guidance. The problem occurs during the infiltration step, where the simulation crashes.
Model Details:

1. In the first step, gravity is applied quasistatically.
2. the quasistatic condition is removed in the second step, and seepage is applied.
3. The model consists of a thin soil layer (10 m depth) overlying a rock layer (20 m depth).
4. The slope has an approximate inclination of 0.3.
5. Hydraulic boundaries are applied at the beginning and end points of the slope.
6. No contact formulation was defined between the soil and rock layers.
7. A 2 cm mesh size is used in the soil zone.

However, the model crashes in the first step of the infiltration process. I have tried various adjustments but have not achieved stable results.
I have been working on this project for nearly six months without success, so I sincerely request your help and expertise to overcome this issue. If it is possible I can also attach the CPS and GOM files for reference.
Please let me know if further details are required, and thank you very much in advance for your support.