I use Zabbix 3.0.2 for monitoring some devices.
It's contain SNMPv3 agent.
On mikrotik i set this settings for SNMP "community" (SNMP user):
authentication-protocol=MD5
encryption-protocol=DES
read-access=yes
security=private
write-access=no
Then the device was rebooted,
i see in log: "v3 err: 3 unknown engine id."
What's the problem - in mikrotik or zabbix - i don't know...
As temporary fix, i change Engine ID on every system boot.
/system script add name=updateEngineID policy=read,write source=":local nowtime [/system clock get time];\r\
\n/snmp set engine-id=\$nowtime;\r\
\n/log info \"SNMPv3 EngineID now is \$nowtime (updated by script)\";"
/system scheduler add disabled=no interval=0s name=updateEngineID on-event="/system script run updateEngineID" policy=read,write start-time=startup