IGV causing generic UI bug

[Randactyl]

Have a problem with Inventory Grid View causing withdraw/deposit to fail with this message:



It's because of this code:

--postHook function for "ZO_InventorySlot_OnMouseEnter"
--Sets the ItemTooltip owner and offset so that tooltips always appear at the 
--beginning of a gridded row.
local function ReinitializeTooltip(inventorySlot)
    local isGrid = inventorySlot.isGrid
    if isGrid == true then
        local gridSize = InventoryGridViewSettings:GetGridSize()
        local col = ((inventorySlot:GetLeft() - 1432) / gridSize) + 1
        local offsetX = -(gridSize * col - gridSize)
 
        ItemTooltip:SetOwner(inventorySlot, RIGHT, offsetX, 0)
    end
end
 
--implementation of general postHook found on ESOUI specific to IGV's purposes
local function IGV_OnMouseEnter_postHook(funcName, callback)
    --"ZO_InventorySlot_OnMouseEnter" is being hooked
    local tmp = _G[funcName]
    _G[funcName] = function(...)
        --ZO_InventorySlot_OnMouseEnter returns true if a tooltip was 
        --successfully shown, false if a tooltip was hidded.
        local returnValue = tmp(...)
        if(returnValue == true) then
            --make ZO_InventorySlot_OnMouseEnter's arguments availible to
            --my function.
            callback(...)
        end
        return returnValue
    end
end
 
IGV_OnMouseEnter_postHook("ZO_InventorySlot_OnMouseEnter", ReinitializeTooltip)

But I'm not sure why. Any ideas?
I need to head to class, but this is all I'll be thinking about