[galvin]

Found a work around.

        local AG = CooldownFrame:CreateAnimationGroup()
        local A = AG:CreateAnimation('Alpha')

        AG:SetLooping('NONE')
        A:SetOrder(1)
        A:SetDuration(0)

        A:SetFromAlpha(1)
        A:SetToAlpha(1)

        CooldownFrame.AG = AG
        CooldownFrame.A = A

Then just do a CooldownFrame.A:Play() before calling SetCooldown()
And now I can use SetHideCountdownNumbers(true), all works now. Hopefully they fix it cause I hate doing hacks like this.