Since the 3.2 version of Grid hasn't been 100% fixed yet i'm posting this for those who need the fix

in your \Interface\Addons\Grid\GridRoster.Lua file you need to make the following edit to line 267(there's 297 lines total)

Change:

if GetCurrentDungeonDifficulty() == 2 then

to:

local raid_diff = GetRaidDifficulty()
if raid_diff == 2 or raid_diff == 4 then