Drowning Orb ignoring Freeze imunity from pantheon.

After first time on the forking rivers map during an Egon map quest series I Shield charged into drowning orb and appeared frozen noted with debug code #3,973,248,150 I tried to replicate during the rest of map area but couldn't. Then during boss fight I nicked the drowning orb and was frozen again. this is noted with debug code #4,015,641,026.