The probe is using pstat_getswap() API which will calculate swap memory for device and file system but not "reserve" and "memory" as shown in the swapinfo command output.
From the command output, "memory" is nothing but a Pseudo swap. It is a swap space, which the operating system recognizes, but in reality it does not exist. It does not exist in memory; it does not exist on disk; it does not exist anywhere. However, the operating system does recognize it, which means more swap space can be reserved than physically exists. The purpose of pseudo swap is to allow more processes to run in memory, than could be supported by the swap device (dev and filesystem).
Here the actual swap memory is dev and filesystem only, that is the reason the probe is not considered reserve and memory data while calculating the swap memory. So probe is working as expected.
Please refer the below article which will explain in detail about the swap memory (swapinfo command).