Thanks a lot! I think we finally found the problem in the automatically downloaded version (see github discussion).
The problem comes from the fact that the indices in the array "Tissue" are not matching the number of tissues defined by "TissueLabels" (= 3). There are some elements that have a Tissue index > 3, which is not supposed to happen with today's version of Brainstorm.
However, this problem is not yet solved, I still get the same error when trying to open the generated meshes