I have the similar situation.
I have a p2p / 30 net and mgmt network without NAT and several SVIs that are connected to the Internet(NAT). In this case, my NTP does not work, because the switch sends packets through these networks(/30 or mgmt) without NAT. Is there a simple way to configure the source IP for NTP after 3 years? (XOS 16.2.5.4 for G1 or XOS 21.1.5.2 for G2)