Like title says. I was using Valkyrie and her Dark Sky (shooting arrows on combine) was doing 0 damage to the boss Nidhogg in the Boss Arena. It may be all bosses, but I wont know until tomorrow as this is the first time it has been this way. I checked the patch notes and don't see any mention of this, so I think it's a bug. I had to switch to another character as this was a huge downgrade.