hi @tmedani, thank you for the prompt reply.
From the image you shared, it seems that you are using the volume grid.
The option force within the Brain is not supported for volume (yet).
So when I check "Force in to layer gray" for a volume model nothing really happens or am I introducing an error? (I am asking becasue I have done it in previous subjects in which the model worked).
A quick solution is to shrink the cortex surface slightly and regenerate the grid for these subjects.
I tried with the steps you provided but it deos not work, I keep getting the same error. Is it possibile that the fact that I am using a "group grid" for group analysis somehow has an impact? I have tried to use a regular grid but the error remains.
Just wanted to add that the fact that I am recomputing the FEM model with ISO2MESH is because running DUNEuro on the original FEM (simNIBS) gives the error coordinate is outside of the grid, or grid is not convex as in this discussion DUNEuro head model computation fails