I did add the data for Y_obs, thanks for pointing that out. It doesn’t solve my problem unfortunately, and I double checked to make sure I included all the variables in the set_data() function.
I can’t supply an update for Y_obs because that is what I’m trying to predict (the election hasn’t happened yet). I guess I don’t understand why there’s an input mismatch in the first place, I’m just updating data to the model, why does it have to match the dimensions of the original model?