there where some sample circuits in the data sheet, showing that Vcm is connected to analog ground, especially when a balanced supply is used.
But at the end of the data sheet the user gets the information to left Vcm open and apply a capacitor of 100nF, if no external signal is connected to Vcm.
I use a balanced supply (+-14V) and want to set Vcm to analog ground. I have two amplifiers in the chain, first did the amplification and the second stage is an active anti aliasing filter. My ADC expects Vcm at analog ground level.
With best regards