How do you get the Hidden Maven Invitation to drop - 30 Domains and counting

This is beyond the realms of bad RNG in into the region of thinking I'm bugged.

Is there any trick to getting The Hidden invitation to drop?

I'm on SSF before someone says to buy it.

Is it more likely in Pure domains than normal ?

I'm getting seriously sick of farming Proxima for splinters, but there really isn't much left worth farming for me at the moment until I get this and the 4th synthesis map.

I have a conjecture that Area Level influences the chance to drop. I'm not sure it's even possible to drop it from normal Breachstones. Based on my conjecture - you should run at least Enriched, ideally Pure Breachstones.

It's just a conjecture, though, so I could definitely be 100% wrong about this.