HP ZBook G3 does not work with MXM to NVMe adapter

[hgtnjpsr]

Recently I obtained a Zbook 17 G3 with no discrete graphics, and I planned to use the MXM slot for other purposes (e.g. additional NVMe drive or 2.5G LAN via a M.2 NIC). However, it appears that the system does not detect the devices connected to the MXM slot. I know power is supplied to the device attached to this adapter because an NVMe SSD warms up when attached, but it is not detectable either as a boot drive or in OS as a secondary drive (both Windows and Linux). The SSD/M.2 LAN still works when it isn't attached to the adapter. On the G3 owners lounge in the old forum, someone had to run BIOS configuration utility to activate their MXM GPU on their G4, but what I'm dealing with isn't a GPU here so I'm not sure how that utility can help. Could it be a whitelist? Lenovo is known to use whitelists on their WWAN slots, but even then you can put 2-lane NVMe SSD in that slot and it would work, so I'm doubting that's the case as well.

 

Any ideas what could be happening? TIA