Real Illusion Illagers aren't affected by the glowing effect when invisible

The glowing effect is set to illusions, but not to the real Illusioner when invisible.

To reproduce give glowing effect:

/effect @e minecraft:glowing 10000 1

/effect @e minecraft:glowing 10000 1

And throw an illusioner with invisibility potion.

As soon as he gets invisibility effect, he creates illusions of himself, but the real one doesn't glow.
Other mobs glow when invisible.