To test the INA 155 I gave a sine wave of amplitude 0.2 V p-p 100Hz. It was operated at 5 V single supply. The reference pin was connected to 2.5 V from an op amp buffer. There seems to be no offset in the output whatever voltage the reference pin is given to. The gain was set at 10 with the pins 1 and 8 open circuited.
The circuit is working fine in simulation.