Reviving an old thread but a data point. I did this today with no issues:

NPE-AKL on one ticket, AKL-SFO-DUB on another. At NPE Premium Check-In I asked the agent if she could interline my bag through to DUB as I had separate tickets. She said no problems and bag tag printed to DUB along with BPs to AKL and SFO. She didn’t know I was Elite as hadn’t given her any info when she said yes.

I didn’t think she would do it as she definitely had an air of “computer says no”. So I was pleasantly surprised