Steps to reproduce:

1. Configure a host to use a macro for its SNMP community, e.g. {$SNMP_COMMUNITY}.
2. On the item configuration page, click Test.
3. Click either the Get value button or the Get value and test button.
4. You will receive an error message since the macros are not expanded.

Result:

For SNMPv1 and SNMPv2c, the error message is:

Timeout while connecting to "address".

For SNMPv3, the error message is:

Cannot connect to "address": Unknown user name.

Expected:

I would expect this to successfully retrieve the value from the device.

This does work correctly if you specify the SNMP credentials directly on the host object without using macros.

I have captured traffic from the Zabbix server and verified that the SNMPv3 security name, for example, is an empty string.