Homing Issues on AXBB-E

[NeeqOne]

I am having issue with homing on my machine using the AXBB-E. The inductive proximity homing sensors fail to activate when X,Y and Z are connection to a single isolated input and the A axis (Y slave) is connected to a different input. When all the switches are connected to different inputs, X and Z homes correctly. However, Y axis does not home until the A the sensor is connected on the same input as Y. This makes it impossible for me to get the gantry squared. I am try fixing this for a couple of days with no success.