Feedback on Mirage Change to stun enemies upon entry: Enemies can leap slam

So I entered a mirage while leveling and discovered that if an enemy has the ability to use "leap slam" or their monster equivalent, they can completely avoid the stun explosion mean't to give the player time to enter the mirage.

It didn't kill me, but it was a surprise. Just figured this was not an intended interaction, but TECHNICALLY not a bug? Since they avoiding a stunning hit by using a movement skill, just an unforseen oversight.