Dear Jorge,

When I run a simple melodic command using the -v option I get the following error:

Removing mean image ... done
Reducing data matrix to a 179 dimensional subspace

Excluding voxels with constant value ... done
Normalising by voxel-wise variance ... done
Data size : 179 x 2145
Starting PCA ... done
Start whitening using 15 dimensions ...
inv(): matrix seems singular

Have you overcome across this error? Moreover single subj ICA runs smoothly (mICA does output ICA components at single subj level). The no convergence error and the inv(): Matrix seems singular error is thrown when I am trying to run group ICA with -a concat option, both via mICA or via melodic command line.