The bug
If an entity, entity-rendered block or translucent world geometry exists behind a phantom which is invisible, they will appear to be in front of the emissive eyes despite being physically further away.
How to reproduce
Place a sign
Give the invisibility effect to a phantom
Look at the sign such that it is positioned behind the phantom's eyes
Expected results
The sign would be occluded by the eyes.
Actual results
The sign occludes the eyes.
Are you using the "fabulous" graphics setting?