It seems that BARON may not give global optimum although the model status is “1 Optimal”. Is it?

When I solve my MINLP model with BARON (to maximize), it gives an OBJECTIVE VALUE 85461884.9974 and the MODEL STATUS is **1 Optimal**. But, if I fix some of the 0-1 variables at the values BARON gives and solve the same model with BARON again, the obtained OBJECTIVE VALUE changes to 85461884.5701 although the MODEL STATUS is still **1 Optimal**. Why?