MSS that are computed by AllMUSes class are not always maximal in the group case
Let us consider the base {b & c, b & d, a & c, -a | -b}, -a | -b being a constraint. MSS should be {b & c , b & d} and {a & c} i.e. {g1,g2} and {g3} but the solver returns {g3}, {g2}, {g1,g2} i.e. {a & c}, {b & d} and {b & d, b & c}. The second set is clearly not a MUS.
This problem might be linked to the use of unitary clauses.