Ubiquiti+zabbix 3.2 snmp - I won't help connect as a node, what's the problem?

Question

SNMP

I'm trying to connect ubiquiti airgrid m2 hp via snmp.
If I execute the command from the zabbix server

snmpget -v 1 -c public -On 192.168.18.30 iso.3.6.1.2.1.11.11.0

I get the output, i.e. snmp works
.1.3.6.1.2.1.11.11.0 = Counter32: 0
But when I add a network node to zabbix, nothing happens - there is no error (and in the server logs), or a successful connection.

Actually what I'm doing wrong or how to get at least an error.
I'm digging deeper.
1) The problem is observed with all snmp devices.
2) with debuglevel =4 displays only these messages.

In get_values_snmp() host:'192.168.18.30' addr:'192.168.18.30' num:1
 SNMP [[email protected]:161]