Thanks - Yes, I assumed it needs to be open, but since they have a LAX to Melbourne flight operating on the same date, that is later than CX881, I assume it will be open.
Having a CX F ticket and boarding pass should grant me entry.

My surprise is that the invitation issued by CX online check in system issued a business class invitation and not a F
I have flow this route previously with similar circumstances, and the invite was always to the Qantas F lounge