Looks like the SimpliSafe motion sensors are passive Infrared (PIR) detectors with a field of vision of 90 degrees that detect motion due to temperature changes. Maybe the heat from the camera is setting it off. Is your camera a V2 or a Pan? Can you move the two further apart? They say they’ve designed the sensor not to be tripped by small animals on the floor, so making the camera a smaller object (further away) may solve your issue.
A second thought is if you have the motion sensor installed in a corner, I believe they mostly sense what is below the sensor. That may give you a safe area to mount the camera above the sensor.