Can you provide more details of the rubber track design, such as the tooth profile geometry. Also what surface feature of the rubber track are you using as a radial constraint to the sprocket? Are you using contact between the opposing faces of each sprocket groove and the track tooth flanks? Are you using contact between the sprocket tooth tips and track tooth roots? Or are you relying on contact between the track tooth tips and the sprocket groove roots?

With a toothed belt, torque is transferred thru contact at the belt/sprocket tooth flank surfaces. But the circumferential path the belt follows around the sprocket is sometimes determined by some other contact. So in order to get the correct contact condition at the tooth flanks, you need to design your sprocket with the correct type, size and profile of feature for radially constraining the belt as it wraps around the sprocket.