On the intermission to 2nd phase when the weather changes, the blue overlay covers pretty much everything, even skillbars, raid frames and minimap which of couse makes it even harder. It does go away after some time though.
Has anyone else encountered this or might know what it is? ElvUI? Some weird WeakAura or BigWigs setting?
Unfortunately, I don't have a screenshot at the time but might be able to upload one once I get home.
Not sure what your issue is without seeing it, but have you tried turning off/down the weather FX on that fight? If you get an addon called Advanced Interface Options and then go to the cvar option, type weather and fog and just set the values to 0 or the lowest. It does make it easier to see in the intermission but I don't know if this will solve your specific issue.