Only the first 4 voices can be used for processing external audio input in Patch Mode - this means that if the 'Ext-In' parameter value is greater than 0 then only 4 voices will be used (the remaining 8 voices being disabled), no matter what the Key Mode and Size parameter values are set to. Please then make sure that the 'Ext-In' parameter is always equal to 0 if you do not want to use the external audio inputs.