If there are several consecutive mdot-operations, Maxima tries to simplify (carry out) this expression from the right and aborts the simplification at the first "unevaluable" operation. I.e.: If a and b are matrices whose (numerical) elements are given and c is not yet defined, then the product "a.b" is carried out in the expression "c.a.b;" but it is not carried out in the expression "a.b.c;". (See also the attached file.)
It would be great if all evaluable operations were carried out in an expression consisting of several mdot-operations.