If a subclass of jdk.jfr.Event is loaded from the CDS archive, before JFR is initialized, this type of events does not function properly. Here's a skeletal example:

java .... -XX:FlightRecorderOptions=retransform=false ... MyTest

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import jdk.jfr.Event;
import jdk.jfr.EventType;

class TestEvent extends Event { }
class MyTest {
    public static void main(String args[]) throws Exception {
        // TestEvent class is loaded *from CDS archive*
        // before recording has started.
        EventType type = EventType.getEventType(TestEvent.class);

        // Start recording
        Recording r = new Recording();

        TestEvent testEvent = new TestEvent();
        testEvent.commit();
        r.stop()

        // At this point, the TestEvent is properly stored in "r" because the
        // testEvent.commit() method was not properly instrumented.