Your data are transposed, that is your 2D array is a Nx1 matrix where you expect an 1xN matrix. There are two ways to solve that problem:
1 - you can transpose your 2D array using the "Transpose 2D Array" primitive located in the Array palette or ... a better solution 2 - You can extract the signal array as a column instead as a row (which it is by default). To do so connect a constant with value 0 to the lower terminal (index(col)) of the Index array primitive that feeds the data to your Build Waveform.
