I think this might have been by design to show the aggregate of all stack traces without an explicit selection, but it's confusing.

From Frank Kriegl:

To reproduce:

1. select the event "flight recording" (A). no stack trace is shown.
2. select the event "Allocation in new TLAB" (B). a stack trace is shown (this is expected)
3. click on (A) again, so the stack trace view is emptied.
4. select the event "Biased Lock Revocation" (C). No events are found, but a stack trace is displayed (this is not expected, compare with the configuration)