The status of SEP client is reflecting as out of date - old virus definition
However the Windows invent log does not show the alert, event ID 40 is missing.
14.3RU1+
In that situation SEP is working as expected. Missing definitions and out-of-date definitions are two different statuses. If the definitions are out-of-date, there is no Event ID 40 for that, Event ID 40 is for the scenarios, when there are no definitions at all.