Nvme drive not being recognised.

[tophneal]

confirm nvme and not sata
>>see for yourself here on aliexpress and also listed compatible in the PBP Wiki (KingSpec NE-512). 
reseat nvme adapter cable
>>done many times
reseat ssd
>>ditto
focus on basic detection by kernel
>>Tried with my stock Debian and 5.6/5.7 Manajaro kernels. Any particular suggestion?

Ordered another PBP nvme adapter as the first version which I received needs 2 folds of the ribbon cable which might be the problem   and also an M.2 NVMe SSD enclosure to verify the SSD.  Hoping between these 2 the issue is further isolated.

My KingSpec disappeared, too (I think I actually added this one to the wiki) and I believe it is due to the folding within the cable. I've it happen a few times, and noticed that if the cable/folds get pinched when putting the bottom case back on, it won't show up until the cable gets moved to avoid the pinching.

EDIT:
So, honestly, my NVMe disappeared after the last time I opened it, months ago. I didn't bother to crack it back open and fix the cable, b/c i thought I had one of the v2.1 cables on the way. Well, I just opened it up, took the crease in my cable, rolled it a bit, to round it off, and the drive is back when booted now! Check that you don't have an actual crease in your cable. I recommend a few pieces of tape to hold it in place without making an actual crease/bend.