Symptom:

Static network nat config command for with mask /32 disappears
from running config after packets pass through it.
NAT still works after this.

Conditions:

This happens for static network nat config command for with mask /32. like
ip nat inside source static network 10.10.10.10 192.168.1.1 /32

Workaround:

Configure equivalent non-network static nat entry, like
ip nat inside source static 10.10.10.10 192.168.1.1

Further Problem Description:

Problem is not present in 12.2 and 12.3 mainline trains.