sometimes the default interface up/down triggers didn't work

[panjie5]

My zabbix version is 3.4.7 , I use the default template (Template Module Interfaces SNMPv2)
But I found sometimes the interface up/down triggers didn't work

How can I fix it?

Expression : {Template Module Interfaces SNMPv2:net.if.status[ifOperStatus.{#SNMPINDEX}].last()}=2 and {Template Module Interfaces SNMPv2:net.if.status[ifOperStatus.{#SNMPINDEX}].diff()}=1