My GoogleFu is weak; ExpressCache

So my son’s laptop (a Lenovo y510p) has two hard drives. The first is a “data” drive (with the OS) while the other is a small M.2 drive which is used to cache the data drive (this is NOT a hybrid drive, although it works like one - they’re two distinct drives kept in different locations).

Somewhere along the way, ExpressCache (the caching software) stopped working (a command line process “eccmd -info” confirmed this). I’d managed to fix it at one point seemingly by random, yet now it’s not working again. This unfortunately leads to ridiculously long startup times for his laptop. Once it’s going, of course, everything runs perfectly fine.

We tried nuking it from orbit, going back to the original factory preset with Windows 8, downloaded countless drivers, updates, etc., but still no dice. All disk checks of numerous varieties seem to say both drives are perfectly intact and healthy.

There are numerous suggestions online giving methods to make this work again. However, here’s the weird part;

Both disks show up in “My Computer” and are fully accessible (and I used tools to run chkdsk, etc. with no problem).
However, in “Diskpart” (using list disk) only his data drive shows so I can’t re-partition
In Disk Manager, only his data drive shows.
In BIOS, only his data drive shows.

I’ve updated the BIOS, updated all applicable drivers, etc… I feel like I’m missing something obvious. Does anyone have any experience with this dastardly fiend of a program?