Dear Sherif,
You can either re-dwonload the simulator, the fux has already been fixed, or just apply the following expression into the +utils/miesmAveragerFast.m
line 170: effective_SINR_dB = 10*log10(mean(mean((10.^(SINR_vector_dB/10))))); -> you have to take twice the mean of SINR_vector
Best regards,
Fjolla