Thank you for your help! I noticed that number format for a2 was set to different one, but no difference, still the solver misbehaves. I tried to downgrade one of the coefficients and run the GRG again but it still doesn’t find find better solution when given all 10 coeffs to the solver. OpenSolver seems to be no-go for me as I’ve found it is not macOS friendly.
Seems that using Evolutionary could do the job. Would you be so kind and send me how to configure the Evolutionary? It is giving me erorreous result with this config. Attachment 636443