Selene monster set not working against dragons?

Sha1rath

I noticed that when wearing the Selene monster set in fights against dragons in Sunspire and in southern Elsweyr, the green bear never attacks the dragon.

(2 items) When you deal Martial melee damage, you call upon a primal spirit that mauls the closest enemy in front of you after 1.3 seconds for 2107 Physical Damage. This effect can occur once every 6 seconds and scales off the higher of your Weapon or Spell Damage.

I think it should. I fight the dragon melee and it is the closest enemy.

Pelanora

What sane bear would take on a dragon.

That bears all: 'dude, you can be mad, I'm over here just killing this spider'

Dragonredux

Someone can probably explain it better than I but...

Any set with a melee requirement or something with at least =< 8 meters doesn't get procced on enemies like Dragons and Daedric Titans due how their hitboxes are. I haven't personally tested Selene but I noticed through sets like Noble Duelist and Grothdaar I have basically be inside them for it to proc which of course is deadly in a Dragon's case. Same goes for other sets like Zaan which I hear often as the same problem.

Zodiarkslayer

It's because the centre of the hitbox is used for distance calculation, not the outside.
There was a thread about this years ago (I don't know if here or on reddit) that basically lined out it is a limitation in the game engine's design.
When the hit box is larger in radius than the 5m melee range, the "melee range" condition in abilities or sets cannot be met, ever.