Bugs on act 3

Hi,

I'm playing with my son I'm co-op mod and we have a very strange game behavior on act 3 in the temple map, the one with sun inside.

The was flashing and we can't see our characters or mobs and dia a couple time till we get to the level boss.

Another one is the sound when we first came to the dark/shadow, don't the name in English.

The second one is solved with a game restart but the other not.

Thanks.