Shannon a colleague of mine recently came across an issue when building a Hyper-V host and pulling down the latest updates. He installed the Intel - Storage Controller - Intel (R) Ethernet Setup Driver for FCoE optional update.
This subsequently removed all NIC Configuration installed on the Hyper-V host and converted the NIC's to FCoE Storage Controllers.
Stay clear of this optional update if you aren't needing to configure FCoE configuration on your Hyper-V host.