Steps to reproduce:

1. Create a new discovery rule
2. Add a test machine IP in "IP Range"
3. Add a check with type "SNMPv2 agent" and SNMP OID "1.3.6.1.2.1.1.2.0"
4. Create a new discovery action
5. Add a new condition: Received value contains "." (without quotes)
6. Add operation: Add to host groups: Discovered hosts

Result:
Host is not added to inventory

If a change discovery action condition to any of these:

  Received value does not contain .

  Received value does not contain 1

  Received value does not contain 1.3.6.1.4.1.8072.3.2.10

  Received value does not contain .1.3.6.1.4.1.8072.3.2.10

The host is added to inventory with group "Discovered hosts" as it should

tcdump output of the monitored machines:

12:22:48.347856 IP X > Y:  C="<redacted>" GetRequest(28)  .1.3.6.1.2.1.1.2.0

12:22:48.349038 IP Y > X:  C="<redacted>" GetResponse(38)  .1.3.6.1.2.1.1.2.0=.1.3.6.1.4.1.8072.3.2.10

Expected:
Host added to inventory