Am I right saying that you have only claddings (no materials properties assigned) in your model? I think that you should replace them with curtain walls that have their self-weight included in the modal analysis.
NO, I was running the model with claddings but also with user defined calculation options for mesh (check the "BONDEK" definition.
I changed BONDEK to "Deck Slab" and it works OK.
Please look at post 5 and the pictures attached there. I'm very sorry if I'm wrong but it seems that you missed the fact that to include self-weight of claddings you have to use load to mass conversion (and switch off use of self-weight in the modal analysis parameters). I made a quick test with the 'right' settings and Bondek panel calculation model assigned to panels 83 and 1931 obtaining similar results for introduced self-weight case case and modal analysis total mass.