I had some problems with a Mac's Fusion Drive. I erased the first MB of the SDD (Terminal in recovery mode). After that I partitioned the SDD again (with GUID). That works. But the HDD is now missing. It doesn't show up on diskutil list and distil cs list says there is no more core storage.
I think the HDD is stuck in the old core storage virtual drive and can't be recognised anymore. But why is diskutil not listing it? I can't believe that exactly that time the HDD failed or is damaged … strange moment :-)
Anyhow, do you know how to get my HDD back?
diskutil list
in your question? It's tough to see what's (not) being recognized from this distance.