Ant+ serial number does not match real device serial

The result of AntPlus Device getProductInfo.serial returns a different serial number for some sensors than the one that actually exists. 

For example, my new speed sensor has the serial number shown in the image:

But getProductInfo.serial delivers -284889340 (minus).
It‘s not a big deal but I would like to fix this.

I assume it has to do with the topic of the following thread.

 RE: ANT Device Numbers? 

But I don‘t really not know how to get the number in a right way…

Any help appreciated!