TOUGH+ 3D model fails to run after uniformly scaling down the mesh

Dear friends, I am currently conducting TOUGH-FLAC3D coupling calculations. I constructed a 100 × 50 × 50 model using FLAC3D, with 15, 7, and 7 grids in three directions respectively. This model can be calculated normally in both separate TOUGH+ calculations and TOUGH-FLAC3D coupling. However, when the number of grids is changed to 20, 9, 9, even without considering the coupling of FLAC3D, TOUGH+ cannot be calculated, and the result file is shown in the following figure. I hope to receive everyone's help.