We Found an Easy Fix!
With the advancement of facial recognitions on the new I-phone X. Some have had issues with unlocking the new iPhone while wearing sunglasses.Each time Face ID is used to unlock your phone, a combination of sensors invisibly project thousands of infrared dots onto your face, before matching these dots to your facial fingerprint, all in a fraction of a second. Most sunglasses still allow the infrared light through for Face ID to verify you are looking at your phone. However, if you happen to own sunglasses that block the specific IR light Apple uses with Face ID, each scan will inevitably fail.
NO WORRIES! HERES THE FIX... (its simple)
In settings under the Face ID & Passcode options you can turn off "Require Attention for Face ID"
Some sunglasses may block attention detection as stated in the instructions.