I've only noticed this happening on Irmansul and tall-like structures you attack, but sometimes you can't even tell if you're doing damage to it because the damage number disappears off of the screen. Like I've been doing Void Ark for months and had no idea that, apart from Sawtooth's stomp, there were times when Irmansul was invincible. I literally did not know that I was doing zero damage because I couldn't see the numbers. It's only like this on the tall structures and I thought the devs should know.