While re-installing my home lab I found something.
I use a homelab with Intel NUC NUC7I7BNH
I use PNY FDI32GEXFITK-EF as boot disk for Intel NUCs. (3 keys – one for each NUC)
I use PNY UCD10 USB Type-C 3.0 / Type A USB 3.0 64GB as ESXi 6.7u1 installer disk
When I boot the Nuc with USB keys plugged we can see all devices but when installing I see this :
We can see that one key is not shown – I though this was a problem with my key so I tested others with same results (I had three identical keys – each for each NUC).
I tested another brand :
You can now see the Sony USB key is visible (we can see the vendor 0 key is the “installer” USB key – NAA is the same as in the previous screenshot.
I re tested : when we use USB keys from the same brand ESXi does not “see” there are many, only one can be used and no other clue can be seen that another is plugged.
I sent an email to VMware security team and they responded : it is not dangerous and « just a bug ». They forwarded it to the right team.
Still, be careful in the meantime.
Hope this helps!