Iptables save -c sometimes emits zero counters. Wanted to understand in which scenarios does this happen?

I have an application to which runs iptables-save periodically. Occasionally i see the counters being emitted as zero values.

Iptable save result at 3 continuous intervals :

Min 1 : [940:73616] -A REQUEST_COUNT -m limit –limit 1000/sec –limit-burst 1000 -j ACCEPT

Min 2 : [0:0] -A REQUEST_COUNT -m limit –limit 1000/sec –limit-burst 1000 -j ACCEPT

Min 3 : [946:73616] -A REQUEST_COUNT -m limit –limit 1000/sec –limit-burst 1000 -j ACCEPT

It is not the ip table restore which is causing the counters become zero as we clearly observe that the counters in the Min 3 the counter is greater than min 1