In scenario host -> zabbix-proxy -> zabbix-server
Snmptrapper configured using perl script by this manual:
https://zabbix.org/wiki/Start_with_SNMP_traps_in_Zabbix
Host is configured to receive traps through proxy - no values comes in, snmptraps are not forwarded from proxy to server.
On proxy trap is being recieved in snmptrapper temp file (/tmp/zabbix_traps.tmp) and if you disable/remove the host on server -> adds unmatched trap to zabbix-proxy.log meaning script passes traps to zabbix-proxy.

Works directly (host -> zabbix server)
Tried the same scenario on 3.0 also everything works.