@tomleslie

It seems that you are right. I expanded the entries in Q^TI_bQ which is a small part of my formulation and IsMatrixShape returned true. Unfortunately, my formula is too long and it seems that maple cannot check the symmetry of whole formula even with expanding. I have attached a small part of relations. In this file you can see another error appeared while checking the whole formula. I will be grateful if you could help me out.

Download SymmetryCheck.mw