nUI is not displaying info when I mouseover a debuff icon on the HUD. nUI version 5.07.29. I would have thought the fix would have been integrated into later versions, but I continue to perform this action manually.
The mouseover option for auras were removed in nUI5 because of the blizzard changes to the aura system to make them secure. You can either use the Aura Button plugin which replaces the left and right aura bars with buttons that are set up as secure already or adjust the layout to turn on the interactivity of the aura bars which will more likely trigger error messages whenever you mouseover the bars during combat.
From what I remember this is being resolved in the nUI6 version but would have, I suspect, meant a big rewrite for nUI5 to implement.