Steps to reproduce:

1. Install zabbix server
2. Add "localhost" with multiple SNMP interfaces
3. Attach SNMP templates with discovery rule(s)
4. Execute discovery

Result:

SNMP items discovered by interface A are always attached to the default interface (in this case B) and can't be moved manually to other interfaces.

See screenshots

Expected:
SNMP items discovered by interface A should be attached to the same interface, not the default one (B), or at the very least one should be able to manually move these items to the correct interface.