Steps to reproduce:

1. Have plain SNMP item: no walk[], no get[], no preprocessing.
2. Remove this physical component so it becomes not supported: No Such Instance currently exists at this OID
3. Network failure

Result:
No new data in item, but item became supported.

Expected:
SNMP item stays unsupported until proof that OID returned.

Log:

5847:20260415:150800.162 enabling SNMP agent checks on host "Hostname": interface became available
5824:20260415:150737.501 item "Hostname:component.status[3]" became not supported: No Such Instance currently exists at this OID
5882:20260415:150700.890 temporarily disabling SNMP agent checks on host "Hostname": interface unavailable
5882:20260415:150653.213 SNMP agent item "sysUpTime" on host "Hostname" failed: another network error, wait for 15 seconds
5882:20260415:150614.890 SNMP agent item "sysUpTime" on host "Hostname" failed: first network error, wait for 15 seconds
5882:20260415:150536.889 enabling SNMP agent checks on host "Hostname": interface became available
5882:20260415:150536.886 temporarily disabling SNMP agent checks on host "Hostname": interface unavailable
5882:20260415:150457.886 SNMP agent item "snmpEngineTime" on host "Hostname" failed: another network error, wait for 15 seconds
5882:20260415:150453.886 SNMP agent item "sysUpTime" on host "Hostname" failed: another network error, wait for 15 seconds
5882:20260415:150414.890 SNMP agent item "sysUpTime" on host "Hostname" failed: first network error, wait for 15 seconds
5882:20260415:150329.870 resuming SNMP agent checks on host "Hostname": connection restored
5824:20260415:150326.267 item "Hostname:component.status[3]" became supported
5882:20260415:150314.894 SNMP agent item "sysUpTime" on host "Hostname" failed: first network error, wait for 15 seconds