Well, I am afraid I have the same issue
I did not expected on my Asus prime X370-ro & 1770x to have the caching enable, but to see 2 devices, one being the QLC flash (1TB) and then the optane 32Gb
But I only see the optane device, not the flash one, like you
I am still looking , there are intel utilities, I can even check the firmware level etc..
But only one device, yet
link to the intel software (for techies):
https://downloadcenter.intel.com/download/29337/Intel-Memory-and-Storage-Tool-CLI-Command-Line-Interface-?product=189227
Normally on an intel plaform you enable the raid in the BIOS and then install RST software
I probably will return it, mine is new
Cheers
Dominique