m15 R1, NVMe support

I have Alienware M15 (just regular one not R2 or R3) and it has two M.2 2280 slots. I also have large battery so 2.5" space is occupied.

I moved one SSD MX500 SATA 1TB (OS) from my other Dell laptop and put it in the first slot and the second slot has Intel 660p 2TB. Everything works.

Now I want to make another drive also 1TB but NVMe with OS and put it in the first slot. Manual says than the first slot supports SATA and NVMe. I also called and chatted with tech support and both said that is the configuration.

So I bought WD 750 1TB gaming drive Gen 3 and my laptop doesn't recognize it in the first slot. It is recognized in the second slot. I cloned MX 500 to the WD drive and installed it in the first slot but it is not recognized.

Even if I put new drive all by itself in the first slot still not recognized.

My warranty just expired. Basically Dell reps confirmed that the slot supports NVMe but it doesn't look like it.

Any ideas what to do?

Thanks.