BARON may not give global optimum although the model status is "1 Optimal"

GAMS
1

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?

2

I would say that numerical error is a likely cause, given that:

( 85461884.9974 - 85461884.5701 ) / (85461884.9974 ) ~= 1 E-9 .

The solver tolerances may very well be higher than this value.