Not sure. I just installed a Rox 9.0 to replace a Cateye Astrale 8. The Cateye cadence magnet works for the Rox. I can't say about the speed sensor because the Cateye is rear wheel and the Rox is front wheel. I've left the Cateye installed until I figure out the much more complicated Rox. Make sure the speed sensor is close enough to the magnet. I lost about 6 miles of a 64-mile ride this weekend because I didn't notice that the speed sensor had move about 1mm during our turnaround stop and it wasn't registering speed or mileage. I little nudge at speed got it working again.
I was having the same problem so I figured the Sigma magnet must be stronger. So I did a test and discovered that the Cateye magnet was 2-3 time stronger than the Sigma. After some head scratching, I replaced the battery in the pickup and all was fine.
1) The longer/ lowered power Sigma magnet is more effective than the shorter, more powerful Cateye magnet. At least with the Sigma pickup it is.
2) This is the second time I've gotten a device with a stale battery (my Specialized computer came with a dead battery). Manufacturers must skimp and ship low quality magnets.
BTW, I really like the size and shape of the Sigma magnets. Seems like it's there for good once you torque down the set screw.