In polyphone patches, the esync connection(s) gives necessary information about the current envelope status back to the MVC module. So, if you are editing a polyphone patch, you have not only to increase the number of voices in the modular shell and use a polyOut module before the AudioOut or a (monophone) Fx module. Also the esync connections of the involved envelope(s) have to be connected to the esyncIn of the MVC, at least the one which is coming out of the envelope that is controlling the last vca before output. If using more envelopes, the esyncAdd2 or 4 modules can be used, or CWM's MVC C, which has four esync inputs.
In monophone patches, the esync outputs of the envelopes do not have to be connected - but the MVCs esyncIn must be connected to it’s gate output (short-circuit), otherwise no sound can be heard.