New rune Demolish hurting invincible towers in parctice tool

I was in the practice tool with kled messing around with the new runes and i turned on tower invincible so the minions would not end the game. But when i attacked the tower with the demolish rune it took the damage. Step-by-step

1. Use the demolish rune (I had it has the secondary one)
2. turn on invincible for the towers
3. attack the towers so far it has happened 100% of the time I've tried it