I have been using the Analog Devices version of Multisim for a while and just downloaded version 12. I modeled a simple amplifier using the AD8429.
Signal on the negative input, positive input grounded, +/-15V, gain resistor of 60.4 ohms for a gain of 100. The AC analysis shows the proper 40dB gain,but shows the gain down 1.5dB at 100 kHz. The AD8229 model shows the same behavior. The data sheet indicates these parts should be very flat out to (at least) 100 kHz at a gain of 100. Maybe just an inaccurate model?